Add tab completion for `-b` and `--branch`
Add docs for enabling tab completion
Fix tab completion script comments
Add debug mode to `twig init-completion`
Add Ruby version to `twig init-completion --debug`
Fix getting bash version in Ubuntu 12.04
Merge branch 'branch_completion' into development

* branch_completion:
  Fix getting bash version in Ubuntu 12.04
  Add Ruby version to `twig init-completion --debug`
  Add debug mode to `twig init-completion`
  Fix tab completion script comments
  Add docs for enabling tab completion
  Add tab completion for `-b` and `--branch`

Conflicts:
	HISTORY.md
	README.md