Enable branch coverage and show report on the command line.

Closes #137

Author: Julian

tox.ini

@@ -11,7 +11,8 @@ deps =
 
 [testenv:coverage]
 commands =
-    coverage run --source jsonschema [] {envbindir}/py.test
+    coverage run --branch --source jsonschema [] {envbindir}/py.test
+    coverage report --show-missing
     coverage html
 deps =
     {[testenv:notpy33]deps}