Merge "Add coverage to test-requirement.txt"

test-requirements.txt

@@ -1,6 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
+coverage>=3.6
 fixtures>=1.3.1
 hacking<0.11,>=0.10.2
 mock>=1.2