The patch removes the neutron-lib from the dependencies. We do not
want/need the consumers of this library to pull in all of the
neutron-lib dependencies.
The patch adds the following:
1. callback to bind is_attr_set - set_is_attr_callback
2. A new exception NsxLibInvalidInput - this is raised when inputs
are invalid.
Change-Id: Ia8ec71dee2d5de921700a9b4fd7e789d2aed4679