Merge pull request #379 from afarra/master

Hookup AyahToolbar
Check in gradle.properties with some signing values.
Improvements to toolbar placement code.

- use NineOldAndroids for animation and View helpers on 2.x
- fix the y position of the toolbar being slightly off
- fix selection on tablet when two pages are showing
- update strings to add open source credits
Update README file
Upgrade to the latest gradle plugin, and use SDK Manager.

Jake Wharton's SDK Manager plugin for Gradle will manage setting up
up local.properties and keeping the various dependencies, sdks, etc
up to date. This should make it easier for people to build.

This fix also helps by making the Crashlytics plugin always enabled,
whereas before, we'd enable it manually for release builds and keep
it disabled for debug builds.
Favor using submenus over using two separate menus.
Move ayah toolbar with page swipes. End Ayah mode when switching to translation view.