Releases for Rush

Add new features to the API and improve documentation:

1. Allow end user to select which rush job they want to run when the rush job argument is not passed.
2. Add Drush Topics documentation for Rush operations.

Select Rush Job Feature

If you do not pass a job argument when running: `drush rush`, then you will be presented with a Drush select list to select which job you want to run.

The source for the job list defaults to your main Rush Application job folder.