Update to new Github bindings with fixed 'watch' action support.
Update version
Make gradle build work without having signing properties set.

Make them optional and read them from a properties file.
Also load language extensions for prettify.

Closes #219.
Enable WebView debugging on debug builds.
Store the last few Github request URLs with the bug reports.

Gives us a slightly better chance of reproducing crashes.
User activity intents can be null, so properly null-check them.
Gist users can be null, so check properly.
Fix NPE.

In case the error view is shown, mPager and mDirStack are both null.
Fix MINT reported NPE.
Allow state loss when switching between repo fragments.

After activity recreation, the navigation index will be restored anyway,
thus also making sure to restore the fragment state.
Move from MINT to Crashlytics.

MINT has a limit on possible sessions, which we almost maxed out. Also
MINT's gradle support is broken, and Crashlytics allows sharing crash
reports.
Switch from ABS to AppCompat support library.

ABS is no longer maintained, and the AppCompat library is the supported
solution (which also means it's supported by the lint tooling etc.).
Update .gitignore.
Assign titles to all menu items.

Closes #221
Fix some inspection warnings.
ActionBarCompat uses metadata for splitActionBar mode.