Introduction of AsyncTasks in RosterFragment

I introduced AsyncTasks for the downloading of data from the Parse
Database so that it will be done in the background and not affect the
main UI thread. This is important so that users do not feel like the
application is frozen after they have logged in and are waiting for the
views to be created.

This version of implementation is found in RosterFragment. EventFragment
is currently disabled until I make sure that the implementation is
safe(no memory leaks, faulty design).
Changed Toast to onPostExecute

Moved the Toast notification from the doinBackground () to onPostExecute
in the Async Task in RosterFragment. This Toast fragment is related to
if the Parse Query fails, and if it did run in doinBackground it would
likely crash the application.
Multi-threading with AsyncTasks

Beta version of multi-threading in application to download data from
Parse database in the background and leaving the main UI thread
uninterrupted by it. Currently only implemented in RosterFragment
Event_Fragment AsyncTask now effectively works

Changed Event_Fragment so the multi-threading for downloading the data
for the expandable list view of events is working properly.
Removed System.sleep(originally for testing)
Formatting issues