ENH: Adds quantopian-quandl bundle as new default.

This data bundle will use the quantopian mirror of the quandl WIKI data
instead of downloading from quandl directly. This dramatically improves
the speed because we do not pay the rate limiting for quandl and we can
send the data in the format zipline expects.

zipline/utils/cache.py

@@ -280,6 +280,13 @@ class working_file(object):
         self._tmpfile = NamedTemporaryFile(*args, **kwargs)
         self._final_path = final_path
 
+    @property
+    def path(self):
+        """Alias for ``name`` to be consistent with
+        :class:`~zipline.utils.cache.working_dir`.
+        """
+        return self._tmpfile.name
+
     def _commit(self):
         """Sync the temporary file to the final path.
         """
@@ -316,13 +323,35 @@ class working_dir(object):
     meaning it has as strong of guarantees as :func:`shutil.copytree`.
     """
     def __init__(self, final_path, *args, **kwargs):
-        self.name = mkdtemp()
+        self.path = mkdtemp()
         self._final_path = final_path
 
+    def mkdir(self, *path_parts):
+        """Create a subdirectory of the working directory.
+
+        Parameters
+        ----------
+        path_parts : iterable[str]
+            The parts of the path after the working directory.
+        """
+        path = self.getpath(*path_parts)
+        os.mkdir(path)
+        return path
+
+    def getpath(self, *path_parts):
+        """Get a path relative to the working directory.
+
+        Parameters
+        ----------
+        path_parts : iterable[str]
+            The parts of the path after the working directory.
+        """
+        return os.path.join(self.path, *path_parts)
+
     def _commit(self):
         """Sync the temporary directory to the final path.
         """
-        copytree(self.name, self._final_path)
+        copytree(self.path, self._final_path)
 
     def __enter__(self):
         return self
@@ -330,4 +359,4 @@ class working_dir(object):
     def __exit__(self, *exc_info):
         if exc_info[0] is None:
             self._commit()
-        rmtree(self.name)
+        rmtree(self.path)