Remove all imports of 'com.github.mobile.R.*'

This keeps Android Studio and Lint happier.
Merge pull request #639 from jonanp/imports

Remove all imports of 'com.github.mobile.R.*'
Revert "Remove all imports of 'com.github.mobile.R.*'"
Merge pull request #640 from github/revert-639-imports

Revert "Remove all imports of 'com.github.mobile.R.*'"
Revert "Revert "Remove all imports of 'com.github.mobile.R.*'""
Merge pull request #641 from github/revert-640-revert-639-imports

Remove all imports of 'com.github.mobile.R.*