Migrate to AndroidX

[bsobe]

• The minSDK version changed with 21
• The Library version updated with 3.0.0
• Added JitPack Support to publish

[yombunker]

I don't understand the need for the minSdk change. I can understand if you want to change to androidX thou.
But, sadly as stated in the main page, this project has been shelved. Roughhike isn't working on it anymore, neither am i.

I saw you changed the github link on the changelog, so might as well just host it yourself and try people to upgrade to your version.