[L4] Bootstrap 3 inline actions block needs 'form-group' class

According to [the Bootstrap 3 documentation](http://getbootstrap.com/css/#forms-inline) the actions in an inline form should either not be wrapped by a div or else the div block containing the actions needs to have the 'form-group' class.
You can see this bug in this [jsfiddle](http://jsfiddle.net/YNWaH/embedded/result/).
This bug should obviously appear in all environments, however I only tested it in L4.

I already fixed this bug and will do a pull request right after posting this issue.
I also included a test to check if this bug persists.

A workaround to this until my pull request gets accepted is to use the following:

    Former::actions()->submit('Foo')->class('form-group');

This is my first issue report and pull request on github, so please be gentle with me.
I hope I did everything right.

Yours sincerely

Sascha Vincent Kurowski