Fragments now correctly restore instance state

-SubmissionsListFragment and CommentsListFragment now save the instance
state for restoration. Device orientation change won’t force fragment
to fetch objects again.
-Realized that fetching submissions sometimes returns more than the
requested number of submissions due to sticky posts. This has been
alleviated for now, but there is a high priority to optimize the list
of submissions and list of comments soon.

-Something I forgot to add to the previous commit: added a new
RestClient implementation using android-async-http library by loop. The
AsyncHttpClient uses the same internal HttpClient from apache’s http
library so code that has been written already (using lots of ugly
AsyncTasks) still work smoothly while new methods can be directly
implemented using the library’s built in async methods.

TODO:
-voting on the comments list view of a submission doesn’t visually
update the submission item in the submissions list view. the user’s
vote is successfully being applied to reddit, but the lack of a visual
cue may cause confusion for end users.