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
Exclude ourself when redirecting to browser.

As our browse filter matches most Github links, Octodroid is (confusing)
also included in the disambiguation list when choosing the 'Open in
browser' option inside Octodroid. Fix that by using our own chooser,
just like we already did when we couldn't open links our intent filter
matched on.
Merge pull request #210 from maniac103/for-upstream

Some fixes for Bugsense reported bugs
Avoid BugSense reported IllegalStateException.

java.lang.IllegalStateException: Recursive entry to executePendingTransactions
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1388)
[...]
at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:276)
at com.gh4a.LoadingFragmentPagerActivity.invalidateFragments(LoadingFragmentPagerActivity.java:30)
at com.gh4a.activities.RepositoryActivity.onTreeSelected(RepositoryActivity.java:295)
at com.gh4a.fragment.ContentListFragment.onItemClick(ContentListFragment.java:104)
at com.gh4a.fragment.ContentListFragment.onItemClick(ContentListFragment.java:1)
at com.gh4a.fragment.ListDataBaseFragment.onListItemClick(ListDataBaseFragment.java:54)
at android.support.v4.app.ListFragment$2.onItemClick(ListFragment.java:58)
at android.widget.AdapterView.performItemClick(AdapterView.java:298)
at android.widget.AbsListView.performItemClick(AbsListView.java:1139)
at android.widget.AbsListView$PerformClick.run(AbsListView.java:3057)
at android.widget.AbsListView$4.run(AbsListView.java:3799)
at android.widget.AbsListView.onDetachedFromWindow(AbsListView.java:2923)
[...]
at android.view.ViewGroup.removeView(ViewGroup.java:3750)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:998)
at android.support.v4.app.FragmentManagerImpl.removeFragment(FragmentManager.java:1171)
[...]
at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:431)
at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:160)
at android.support.v4.view.ViewPager.dataSetChanged(ViewPager.java:703)
at android.support.v4.view.ViewPager$PagerObserver.onChanged(ViewPager.java:2060)
at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
at android.support.v4.view.PagerAdapter.notifyDataSetChanged(PagerAdapter.java:276)
at com.gh4a.LoadingFragmentPagerActivity.invalidateFragments(LoadingFragmentPagerActivity.java:30)
at com.gh4a.activities.RepositoryActivity.onBackPressed(RepositoryActivity.java:319)
[...]
Switch to new Github bindings.

Those fixed URL encoding for content list fetching; fetching contents
for paths with spaces now works.
Upgrade prettify to latest version.
Use screen estate better in diff view.

Shrink the huge padding to the left (and right), and make font sizes
somewhat consistent to prettified code output.

In case we need larger fonts at some point, this should probably happen
in the form of a default zoom level option.
Adjust foreground color of change headers in light theme.
Fix BugSense reported NPE.
Merge pull request #212 from maniac103/for-upstream

Fixes and improvements
Feature to add a comment on the line
Edit and delete comment on the line
Confirm before delete comment and UI improvements
Feature to add a comment on the line
String improvements.
Improve comment dialog behaviour.
New "Files" tab at pull request and tidy up commit comment and review comment
Refactor file viewer classes