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
Merge pull request #200 from tpena/enhancement/Greece-mobile-splitting

Use a 3,4 split for Greek mobile numbers