Values used in timestamps are in milliseconds instead of seconds as documented

[markbirbeck]

The values used in atime, ctime and mtime (automatically created when using the timestamps() method) are documented as being Unix time, but are actually milliseconds:

resourceful/lib/resourceful/resource.js

Line 862 in 2f1525c

// see: http://en.wikipedia.org/wiki/Unix_time

Do we want to change the documentation so that it's no longer Unix time, or do we want to modify the code to match the documentation?