Lots of updates

- gallery field now updates metadata
- repeater / flex post data with keys, not names
- fixed acf.nonce not on all edit screens

Signed-off-by: Elliot Condon <e@elliotcondon.com>
Removed acf.nonce from acf_form_head

Signed-off-by: Elliot Condon <e@elliotcondon.com>