Issue #10: Implemented CookieStore for persistant storage of session cookies.

Persistant stoage of cookies are made avaliable through the CookieStore singleton, and changes made to facilitate this transition were made.
Issue #10: Flush functionality and caching added to CookieStore.

The CookieStore now caches the cookie string to memory instead of reading from disk through a SharedPreference each time. The store can also now be flushed, removing both the cached copy from memorgy and the Preference key-value pair on disk.
Merge branch 'new/cookiestore' of github.com:hpxro7/UWSchedule into new/cookiestore

Conflicts:
	UWSchedule/src/main/java/com/amgems/uwschedule/api/uw/CookieStore.java
	UWSchedule/src/main/java/com/amgems/uwschedule/ui/HomeActivity.java
	UWSchedule/src/main/java/com/amgems/uwschedule/ui/LoginActivity.java