Removed scrollDefaultNow, scrollDefaultTime; added scrollDefault

The scrollDefaultNow and scrollDefault options have been consolidated into a single scrollDefault option.
Tweaked typeahead to better guess am/pm values

If a scrollDefault or minTime is set and no am/pm is provided when using 12-hour time, the scrollDefault/minTime will be used to guess am/pm. For example, if the scrollDefault is 10:00am and the user enters '5', timepicker will guess that means 5:00pm, not 5:00am. Closes #264