Implement the 'version' sub-command

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>
Make 'review', 'submit', and 'abandon' checkout upstream

Successful executions of these commands, when performed in a
change-branch, checkout upstream and delete the change-branch. This is
usually what the user want to do anyway. A --keep option can avoid
this if the user wants.

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>
Improve workflow documentation

Signed-off-by: Gustavo L. de M. Chaves <gnustavo@cpan.org>