Use a 3,4 split for Greek mobile numbers

According to http://www.itu.int/dms_pub/itu-t/oth/02/02/T02020000550001MSWE.doc, the formatting for mobile numbers follows a 3,4 split. e.g. +30 693 XXX XXXX. This is also how mobile numbers are listed in the Non-geographic numbers section of the wiki http://en.wikipedia.org/wiki/Telephone_numbers_in_Greece. I've updated the mobile matcher for Greece as well as the rspec.