Updated to be able to access all bags.

For ability to have a generic error handler for all bags in case they are grouped like `register[email]`. It's not possible to know what the grouping is unless `$errors->register->getMessages()` is specifically called.
Corrected Function Comment
Merge pull request #6151 from websanova/4.2

[4.2] Updated To Be Able To Access All Bags
Merge branch '4.2'
Merge branch 'master' of github.com:laravel/framework