Added new JS action 'submit'

Signed-off-by: Elliot Condon <e@elliotcondon.com>
Improved efficiency when saving a field group

Signed-off-by: Elliot Condon <e@elliotcondon.com>
Added custom fields to gallery sidebar

https://github.com/AdvancedCustomFields/acf5-beta/issues/87
Signed-off-by: Elliot Condon <e@elliotcondon.com>