Devoncarew pub get

Some pub get changes:

- temporarily comment out the tavern dependency. Our compiled size goes from 23MB to 10.4MB (pub uses mirrors w/o the mirrors used annotation)
- move the pub context menu around a bit in the context menu, to try and reduce the overall size of the context menu
- have `pub get` applies to project's w/ a pubspec.yaml file, as well as to the pubspec file itself

@keertip for review