change Gemfile to make rake work locally & update coverage

Author: pascalwengerter

Gemfile.lock

@@ -159,7 +159,7 @@ GEM
       method_source
       rake (>= 0.8.7)
       thor (>= 0.19.0, < 2.0)
-    rake (12.3.1)
+    rake (12.3.2)
     reform (2.2.4)
       disposable (>= 0.4.1)
       representable (>= 2.4.0, < 3.1.0)