Created NewsContract, swipe to refresh

Using that Contract pattern thing, so other classes updated accordingly.
NewsDbHelper is now NewsDatabase.
And swipe-to-refresh because hecking !!! I mean, better than showing a
toast.
Miscellaneous cleanup

Added KEY_ prefixes to keys in EighthContract, changed access modifiers,
moved DividerItemDecoration to .util, other things.
One good thing I forgot to note is that invalidating the auth token in
ScheduleFragment works! As noted by not having to log in 1000 times.
Cool.