implements container.formGroupClass parameter

[skie]

Implements container.formGroupClass parameter to pass or disable classes different from form-group to containers.

When defined complex fields that should have their own containers, now possible to assign the .form-group class at wrapper level, while the inner fields rendered by FriendsOfCake/bootstrap-ui would not have it.

[ADmad]

This line will generate an undefined index error if the unset() on line 670 is executed. Test case for when $skipFormGroupClass ends up being true is needed.

P.S. I have fixed the test suite issues on upstream master, so you can rebase.

[ADmad]

I am a bit unsure about these approach. This increases the if/else conditions and makes the code more difficult to follow/maintain in the long run. The idea behind using string templates was avoid this problem.

Instead of appending the formGroupClass to containerClass, how about replacing the hardcoded form-group in the templates, with a new template var formGroupClass? Default it to form-group and override with user provided value if required. I am pretty sure that will require minimal code changes.

[skie]

new approach in separate pull requiest #406