Add DateTime utility class that moves the date parsing features out of G...

...raphHandler and CliQuery where they can be shared by the API and other tools.

Add millsecond absolute timestamp parsing
Add month relative time option with the "n" character that works over 30 day periods
Factored the date/time specific calls out of GraphHandler
Modified CliQuery to use the new date/time parsing so folks can now enter relative or timestamps via the command line
Add unit test class for DateTime.java