Ability to remove something we added

[amolghotankar]

I added a new module and realized I did something wrong but it had already added new files and changed few files in both test & app.

I was looking for some command to remove it but had to manually search all the files & its references and then delete it.

[34r7h]

+1 this would be a standout feature. maybe it would work with 'undo' or 'remove' flags like yo ng-poly:d example -undo or yo ng-poly:m example -remove with a confirmation prompt that all sub-modules/directives/controllers/etc will also be removed.