Change action-type when editing action, 85% ready

Not 100% working yet, but can be tested from left-most "Edit-action"-icon,
and clicking either ActionTypeID 2 or ActionTypeID 4 links.
These make ajax request to actions/edit_test and render generic
action-form element from View/Elements/generic-action-form.ctp.

This generic action form maybe can later be used to create all action
forms.