Update Arabic language

Update Arabic language
Updating Arabic language and minimize weekdaysShort
Merge branch 'develop' of https://github.com/xsoh/moment into develop

Conflicts:
	test/lang/ar.js
Fixed greek "previous Saturday" string - was gender female, now is gender neutral
fixed message in a test
comply with Travis
reverted the 'min' directory to its original state
Merge pull request #1622 from akarelas/akarelas-fixGreekCalendar

Fix "previous Saturday" in greek string

@changelog
@section bugfix
Merge pull request #1559 from xsoh/develop

Updating Arabic language
Implement accurate moment.duration({from, to})
Better bubbling of days to years in duration
Use duration object in relativeTime
internal relativeTime now accepts only duration object