[BUGFIX] Indent/outdent does not work if formatblock button is disabled

Problem: If the "formatblock" button is disabled, the current paragraph
gets a css class "indent" but a wrapping div is not created with that
css class.

Solution: When formatblock is not configured, allow all standard block
elements. When formatblock and indent are both configured, ensure div is
allowed.

Change-Id: I8f74e453f96968940f67652e075a976f0104f2c8
Resolves: #28903
Releases: 4.5, 4.6
Reviewed-on: http://review.typo3.org/4322
Reviewed-by: Stanislas Rolland
Tested-by: Stanislas Rolland