Get rid of hours/minutes in nightly versions

To get around chrome's "subversions can't start with zero", I was using
hour+1 (1-24 versus 0-23). However, this breaks at midnight (midnight of
the previous day will be after the entire next day).

Instead, just use yyy.M.d (2013.11.02).
Use a nightly target instead of a property

This makes building nightlies a little more user friendly.