Merge branch 'apk-extension-obb-support' into 'master'

support APK Extension OBB files

Google Play specifies OBB aka "APK Extension" files for apps that need more than 100 MBs, which is the Play APK size limit.  They also provide a mechanism to deliver large data blobs that do not need to be part of the APK.  For example, a game's assets do not need to change often, so they can be shipped as an OBB, then APK updates do not need to include all those assets for each update.

https://developer.android.com/google/play/expansion-files.html

See merge request !143