Update the configuration and the associated code to be more consistent in the
time and size units used for various purposes.  A new set of constants have
been added to allow the same units to be used throughout the code, including
providing both full and abbreviated unit names.

In addition, the ds-cfg-time-limit and ds-cfg-profile-sample-interval
attributes have been updated so that they use the integer with unit format
rather than just an integer with an implied unit.

OpenDS Issue Number:  559