Added convenience functions to example HumanUser class

Added functions for retrieving a users notes and tickets. Reworked the args for
tasks to be like the new notes and tickets calls.
SgVersion added arg "sgFields" to version functions

SgVersion functions that return other Version Entities now have an arg
"sgFields" for specifiying the fields to prefill the result(s) with.

Also made the functions subVersion() and version() compare the version being
requested and if its the version of the parent entity they return self.
Ticket class now checks if exists, raises during close() and reply()

Ticket class will check if the Entity exists when calling close() and
reply().  Raises a RuntimeError() if not.