Change user-add's uid & gid parameters from autofill to optional.
Change the DNA magic value to -1.
For old clients, which will still send 999 when they want DNA
assignment, translate the 999 to -1. This is done via a new
capability, optional_uid_params.
Tests included
https://fedorahosted.org/freeipa/ticket/2886
In order to run the tests you must put your DM password into
~/.ipa/.dmpw
Some tests are expected to generate errors. Don't let any ERROR
messages from the updater fool you, watch the pass/fail of the nosetests.