* Prepare welcome wizard related to issues
https://github.com/syncthing/syncthing-android/issues/1129https://github.com/syncthing/syncthing-android/issues/622
* Add drawables and texts
* Disable scrolling the ViewPager, we have buttons for that
* Add welcome wizard code
Ask for storage and location permission
Location permission is required to run the app
Recheck storage permission on each app start, if revoked the
welcome slides show again.
* Review
* Review - Do not quit the app when storage permission is not granted
* Review - Minor string improvements
* Moved launcher icons from drawable to mipmap
* Added alternative drawable resource
* Added background and foreground layers
* Changed refernce in manifest to mipmap
* Updated background