Added refresh to Friends list + cached swipe.

Refactored the dataholder class a little so that it uses the get
instance call.  I think this helps with performance (it is not a static
class on the stack, but a static object on the heap?).  Also cached the
swiping by adding setOffscreenLimit to 3 on the viewpager.  It makes
more sense if this value was 2, but the swiping seemed less laggy on my
phone at 3.