Add v.2.0.17 to f-droid

[flxholle]

Hi @timusus, Shuttle Music is now available on f-droid: https://f-droid.org/en/packages/com.simplecity.amp_pro/ This pull request includes the new commits from the release-branch and a longer app description. Furthermore the versionname has to be moved from Config to the gradle file to enable auto updates for f-droid. After you have merged this, please create a new tag fdroid-v2.0.17 from the fdroid-branch.

Closes #326 Closes #28