Remove trailing dot from abbreviated month names

According to the CLDR the Greek abbreviated month names should not contain a
trailing dot.

http://www.unicode.org/cldr/charts/by_type/calendars.gregorian.html#360c210ad4f23085
Fix abbreviated month names according to CLDR

http://www.unicode.org/cldr/charts/by_type/calendars.gregorian.html#Months:_format-abbreviated
Fix abbreviated day names according to CLDR

http://www.unicode.org/cldr/charts/by_type/calendars.gregorian.html#Days:_format-abbreviated
Fix am / pm code according to CLDR

http://www.unicode.org/cldr/charts/by_type/calendars.gregorian.html#5c6d3896851453de
http://www.unicode.org/cldr/charts/by_type/calendars.gregorian.html#72c7f54616968b69
Correct the singular phrase as well
Fix number currency format according to CLDR
Merge pull request #313 from fotos/update_el_cldr

Update el according to CLDR