Merge pull request #206 from maniac103/for-upstream

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Fix some Bugsense-reported exceptions.
Update to latest version of Android Studio.
Clean up ExploreActivity.

This should hopefully fix this Bugsense-reported exception:

The application's PagerAdapter changed the adapter's contents without
calling PagerAdapter#notifyDataSetChanged! Expected adapter item count:
1, found: 3 Pager id: com.gh4a:id/pager Pager class: class
android.support.v4.view.ViewPager Problematic adapter: class
com.gh4a.activities.ExploreActivity$ThisPageAdapter