Release in f-droid app store

[christoph-buente]

There is a very old version of android release in this independent android app store. Please consider to release the current version too, so people without an google account can install wheelmap too.

https://f-droid.org/repository/browse/?fdfilter=wheelmap&fdid=org.wheelmap.android.online

[ghost]

Looks like it requires play-services, a non-free Google library now. Maybe there could be a gradle flavor that doesnt need that? Also: Jar files should be replaced by maven depencies from jcenter/mavencentral/jitpack or build from source.