Changed the field_group script in order to change how keys are stored in the database.

I've been frustated that I have to cross reference my values against
keys against keys so I've adjusted so, instead, keys will be prfaced
with the namespace 'acf_' followed by the key's name and a number if
the key is already taken.
Changing How Keys are Labled in the WPDB

I have never liked how ACF generates generic 'field_#' keys instead of
something based on the field's name, Here is my first attempt at
makigng that happen.