Add preferences

Prepare app for Settings and general code cleanup.

PS 2: Allow Activity to launch & reorganize settings

Change-Id: Ib8fe508a29b7a43d550eee85ae560503369f2a5e
Add License

This project is licensed under the GPLv3

Change-Id: I235c0808b9fa31267c97dd07c75baf56362fbc90