Refactored all sharedPreferences access into its own class.
Fix Dropbox login loop
Updated UI for tablet landscape mode
Merge pull request #391 from chuckbjones/fix-dropbox-login-loop

Fix dropbox login loop, and sharedPrefs refactor, closes #278
Merge pull request #392 from mpcjanssen/tablet-drawer

Automatically show nav drawer in landscape mode on tablets
Show drawer in AddTask in tablet landscape view
Merge pull request #398 from mpcjanssen/issue-395

Show Add tasks navigation drawer in tablet landscape view, closes #394
Update ActionBar-PullToRefresh to v0.5. Show refreshing when manually refresh.
Version 2.1, release 50