Make the authentication flow cleaner. Remember the last account used.
New:
* ObjectService: Provides caching of known Activity Objects
* ObjectActivity: An activity which shows an Activity Object! Woo! At last!
* CommentAdapter: Used for displaying comment threads
Changes:
 * FeedService will now watch the main feeds of all of your accounts in the background
 * Extracted some common Accuount information out into ActivityWithAccount
Added dependency:
* DiskLRUCache. Also licensed under Apache 2.0
Bump version:
 * v0.2.1