[AdminBundle] Added a WYSIWYG form type

[denbatte]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Fixed tickets	#212

TODO

• Submit changes to the documentation

WHAT
A new wysiwyg form type has been created in the Adminbundle.
This makes it possible to use 'wysiwig' in the formbuilder as a type and results in a text area with a wysiwyg editor on top. There are two extra options you can pass as a data attribute:

• simple: will only render a basic wysiwyg editor
• full: will render a wysiwyg editor with extra buttons
  The wysiwyg formtype also replaces the rich text type when generating a new pagepart using the kunstmaan generatorbundle.

WHY
Before this feature there was:

        $builder->add('name', 'textarea',
                array(
                    'attr' => array(
                        'rows'  => 5,
                        'cols'  => 600,
                        'class' => 'js-rich-editor rich-editor'
                    )
                )
        );

now you just have to use:

        $builder->add('name', 'wysiwyg');

[roderik]

@denbatte please add a changelog item? Check with @Devolicious on how