- Make usage language more accurate by stating "repositories"

- Have usage counter be based on a 4 weeks TTL
- Add a simple usage counter breakage test

config.py

@@ -188,4 +188,4 @@ class DefaultConfig(object):
   LOG_ARCHIVE_PATH = 'logarchive/'
 
   # For enterprise:
-  MAXIMUM_CONTAINER_USAGE = 20
+  MAXIMUM_REPOSITORY_USAGE = 20