CLC-1241 Get count of unread bMail messages
https://jira.media.berkeley.edu/jira/browse/CLC-1241

Huge thanks to Yu-Hung for the great refactoring work on this.
CLC-1241 Get count of unread bMail messages

- Moved logging line into the proxy
- Moved atom_feed reference into settings
CLC-1241 Show count of unread bMail messages

- Removed the inheritance from BaseProxy
- Added MyBadges::GoogleMail into the cache expiration list
Merge pull request #908 from shacker/CLC-1241e

CLC-1241 Get count of unread bMail messages