try an SVG for a nicer look

Author: wojcikstefan

README.rst

@@ -7,8 +7,8 @@ Flask-MongoEngine
 .. image:: https://travis-ci.org/MongoEngine/flask-mongoengine.svg?branch=master
   :target: https://travis-ci.org/MongoEngine/flask-mongoengine
 
-.. image:: https://coveralls.io/repos/MongoEngine/flask-mongoengine/badge.png?branch=master
-  :target: https://coveralls.io/r/MongoEngine/flask-mongoengine?branch=master
+.. image:: https://coveralls.io/repos/github/MongoEngine/flask-mongoengine/badge.svg?branch=master
+  :target: https://coveralls.io/github/MongoEngine/flask-mongoengine?branch=master
 
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