Add Samsung support-v7 workaround config

[juliocotta]

Hi, you could add the proguard config to avoid a bug in some samsung phones
https://code.google.com/p/android/issues/detail?id=78377

something like this
# https://phabricator.wikimedia.org/T78197:
# NoClassDefFoundError: android.support.v7.internal.view.menu.MenuBuilder
# http://stackoverflow.com/questions/26657348/appcompat-v7-v21-0-0-causing-crash-on-samsung-devices-with-android-v4-2-2
# Allow obfuscation of android.support.v7.internal.view.menu.** but not the rest of android.support
# to avoid problem on Samsung 4.2.2 devices with appcompat v21
# see https://code.google.com/p/android/issues/detail?id=78377#hc150
-keep class !android.support.v7.internal.view.menu.MenuBuilder
-keep class !android.support.v7.internal.view.menu.SubMenuBuilder

from: https://github.com/wikimedia/apps-android-wikipedia/blob/master/wikipedia/proguard-rules.pro

[krschultz]

I'm interested in doing this, but I'm thinking about where it should go in the repo. It's not quite a library, i.e. I wouldn't want to put it in the android support v7 config. I'm open to suggestions.

[krschultz]

Also I changed the title of the issue, this is not a problem with the support v7 lib or its proguard config.