YAPF, take 3 (#2098)

* Use pep8 style

The original style file is actually just pep8 style, but with everything
spelled out. It's easier to use the `based_on_style` feature. Any overrides are
clearer that way.

* Improve yapf script

1. Do formatting in parallel
2. Lint RLlib
3. Use .style.yapf file

* Pull out expressions into variables

* Don't format rllib

* Don't allow splits in dicts

* Apply yapf

* Disallow single line if-statements

* Use arithmetic comparison

* Simplify checking for changed files

* Pull out expr into var

test/runtest.py

@@ -180,14 +180,15 @@ LIST_OBJECTS = [[obj] for obj in BASE_OBJECTS]
 TUPLE_OBJECTS = [(obj, ) for obj in BASE_OBJECTS]
 # The check that type(obj).__module__ != "numpy" should be unnecessary, but
 # otherwise this seems to fail on Mac OS X on Travis.
-DICT_OBJECTS = ([{
-    obj: obj
-} for obj in PRIMITIVE_OBJECTS if (
-    obj.__hash__ is not None and type(obj).__module__ != "numpy")] + [{
-        0: obj
-    } for obj in BASE_OBJECTS] + [{
-        Foo(123): Foo(456)
-    }])
+DICT_OBJECTS = (
+    [{
+        obj: obj
+    } for obj in PRIMITIVE_OBJECTS
+     if (obj.__hash__ is not None and type(obj).__module__ != "numpy")] + [{
+         0: obj
+     } for obj in BASE_OBJECTS] + [{
+         Foo(123): Foo(456)
+     }])
 
 RAY_TEST_OBJECTS = BASE_OBJECTS + LIST_OBJECTS + TUPLE_OBJECTS + DICT_OBJECTS
 
@@ -720,8 +721,8 @@ class APITest(unittest.TestCase):
         assert ray.get([id1, id2, id3]) == [0, 1, 2]
         assert ray.get(
             g._submit(
-                args=[], num_cpus=1, num_gpus=1, resources={"Custom":
-                                                            1})) == [0]
+                args=[], num_cpus=1, num_gpus=1,
+                resources={"Custom": 1})) == [0]
         infeasible_id = g._submit(args=[], resources={"NonexistentCustom": 1})
         ready_ids, remaining_ids = ray.wait([infeasible_id], timeout=50)
         assert len(ready_ids) == 0