OPEN - issue CORE-4295: DE System Messages menu item should display
unread message count 
https://pods.iplantcollaborative.org/jira/browse/CORE-4295

Added logic for parsing the new response from the count-messages
endpoint.  

An event is triggered indicating the unseen system messages count has
been updated.
Merge branch 'master' of
https://github.com/iPlantCollaborativeOpenSource/de-webapp.git