Replace special single quote with regular single quote. (#1693)

CONTRIBUTING.rst

@@ -11,7 +11,7 @@ mailing list `ray-dev@googlegroups.com`_.
 To contribute a patch:
 ----------------------
 
-1. Break your work into small, single-purpose patches if possible. It’s much
+1. Break your work into small, single-purpose patches if possible. It's much
    harder to merge in a large change with a lot of disjoint features.
 2. Submit the patch as a GitHub pull request against the master branch.
 3. Make sure that your code passes the unit tests.

python/ray/dataframe/dataframe.py

@@ -741,8 +741,8 @@ class DataFrame(object):
         Args:
             labels: Index or column labels to drop.
 
-            axis: Whether to drop labels from the index (0 / ‘index’) or
-                columns (1 / ‘columns’).
+            axis: Whether to drop labels from the index (0 / 'index') or
+                columns (1 / 'columns').
 
             index, columns: Alternative to specifying axis (labels, axis=1 is
                 equivalent to columns=labels).
@@ -751,7 +751,7 @@ class DataFrame(object):
 
             inplace: If True, do operation inplace and return None.
 
-            errors: If ‘ignore’, suppress error and existing labels are
+            errors: If 'ignore', suppress error and existing labels are
                 dropped.
         Returns:
             dropped : type of caller
@@ -972,7 +972,7 @@ class DataFrame(object):
                 backfill.
                 bfill: use NEXT valid observation to fill gap.
 
-            axis: 0 or ‘index’, 1 or ‘columns’.
+            axis: 0 or 'index', 1 or 'columns'.
 
             inplace: If True, fill in place. Note: this will modify any other
                 views on this object.
@@ -986,7 +986,7 @@ class DataFrame(object):
                 than 0 if not None.
 
             downcast: A dict of item->dtype of what to downcast if possible,
-                or the string ‘infer’ which will try to downcast to an
+                or the string 'infer' which will try to downcast to an
                 appropriate equal type.
 
         Returns:

site/_posts/2017-08-08-plasma-in-memory-object-store.markdown

@@ -112,7 +112,7 @@ with the Plasma store via messages serialized using [Google Flatbuffers][4].
 
 Plasma is a work in progress, and the API is currently unstable. Today Plasma is
 primarily used in [Ray][2] as an in-memory cache for Arrow serialized objects.
-We are looking for a broader set of use cases to help refine Plasma’s API. In
+We are looking for a broader set of use cases to help refine Plasma's API. In
 addition, we are looking for contributions in a variety of areas including
 improving performance and building other language bindings. Please let us know
 if you are interested in getting involved with the project.

site/_posts/2017-10-15-fast-python-serialization-with-ray-and-arrow.markdown

@@ -58,19 +58,19 @@ objects to and from the Arrow format. Some properties of this approach:
 reading the full object (requirements 1 and 4).
 - Arrow supports **zero-copy reads**, so objects can naturally be stored in
 shared memory and used by multiple processes (requirements 1 and 3).
-- We can naturally fall back to pickle for anything we can’t handle well
+- We can naturally fall back to pickle for anything we can't handle well
 (requirement 2).
 
 **Alternatives to Arrow:** We could have built on top of
 [**Protocol Buffers**][5], but protocol buffers really isn't designed for
-numerical data, and that approach wouldn’t satisfy 1, 3, or 4. Building on top
+numerical data, and that approach wouldn't satisfy 1, 3, or 4. Building on top
 of [**Flatbuffers**][6] actually could be made to work, but it would have
 required implementing a lot of the facilities that Arrow already has and we
 preferred a columnar data layout more optimized for big data.
 
 ## Speedups
 
-Here we show some performance improvements over Python’s pickle module. The
+Here we show some performance improvements over Python's pickle module. The
 experiments were done using `pickle.HIGHEST_PROTOCOL`. Code for generating these
 plots is included at the end of the post.
 

site/_posts/2017-11-30-ray-0.3-release.markdown

@@ -96,9 +96,9 @@ cd ray/python/ray/rllib
 ## Distributed Actor Handles
 
 Ray 0.3 adds support for [distributed actor handles][1], that is, the ability to
-have multiple callers invoke methods on the same actor. The actor’s creator may
+have multiple callers invoke methods on the same actor. The actor's creator may
 pass the actor handle as an argument to other tasks or to other actor methods.
-Here’s an example in which the driver creates an actor to log messages and
+Here's an example in which the driver creates an actor to log messages and
 passes an actor handle to other tasks:
 
 ```python

src/ray/raylet/lineage_cache.h

@@ -34,7 +34,7 @@ class LineageCache {
   LineageCache();
 
   /// Add a task and its object outputs asynchronously to the GCS. This
-  /// overwrites the task’s mutable fields in the execution specification.
+  /// overwrites the task's mutable fields in the execution specification.
   ///
   /// \param task The task to add.
   /// \return Status.