Still needs some better assets for the actual donate buttons, but now it includes
the relevant text about donating to developers. It also puts the donation options
in a grid layout and lets them flow across so that if there is more than three, they
will end up on the second line.
This makes it a lot easier to setup all the testing stuff. Mostly,
I'm tired of fighting Android Studio's fragility, so I want to remove
as much non-standardness as possible in the hopes of improving that
situation.
closes#534https://gitlab.com/fdroid/fdroidclient/issues/534
