Bug 1194365 - Bump Andoid NDK to r10e; manually install Android SDK and NDK on Mac OS X. r=mcomella

This bumps the NDK version to r10e.

Previously, we used brew to install android-sdk and a custom version
of android-ndk.  That makes it hard to control the installed versions.
This installs from downloaded archives, which unifies the Mac OS X
approach with the straight-forward Linux approach.

python/mozboot/bin/bootstrap.py

@@ -32,7 +32,6 @@ REPOSITORY_PATH_PREFIX = 'python/mozboot'
 
 REPOSITORY_PATHS = [
     'mozboot/__init__.py',
-    'mozboot/android-ndk.rb',
     'mozboot/android.py',
     'mozboot/archlinux.py',
     'mozboot/base.py',