Remove override of doRun() so the help option works.
Merge pull request #138 from pjcdawkins/fix/help-option

Remove override of doRun() so the help option works.
Improve checkout command usability.
Improve choosing environments in get command.
Mark the current environment in the checkout options.
List environments if 'platform branch' is called with no arguments.
String consistency
Merge branch 'cache-environments' into mine

Conflicts:
	src/Command/ProjectGetCommand.php