#78 Add time resolution

[Brian Carrier]

Add a way to query the system to find out what the resolution is for the given file system (i.e. some FAT times are to do the day and some are to the 2 seconds).

See:
https://sourceforge.net/mailarchive/forum.php?thread_name=4E03F6BA-19D2-4D64-A7A9-B42ACCFDE707%40acm.org&forum_name=sleuthkit-users