feat(circleci): support parallel builds in the client (#106)

* Add support for parallel builds.

* Send boolean True. Not string.

coveralls/api.py

@@ -73,6 +73,10 @@ def __init__(self, token_required=True, **kwargs):
         if os.environ.get('COVERALLS_REPO_TOKEN', None):
             self.config['repo_token'] = os.environ.get('COVERALLS_REPO_TOKEN')
 
+        parallel = os.environ.get('COVERALLS_PARALLEL', '')
+        if parallel.lower() == 'true':
+            self.config['parallel'] = True
+
         if token_required and not self.config.get('repo_token') and not is_travis_or_circle:
             raise CoverallsException(
                 'Not on Travis or CircleCI. You have to provide either repo_token in %s '
@@ -164,7 +168,8 @@ def create_data(self, extra=None):
                         "source": "def seven\n  eight\n  nine\nend",
                         "coverage": [null, 1, 0, null]
                     }
-                ]
+                ],
+                "parallel": True
             }
         """
         if not self._data: