move attributes of v3.client.Client into alphabetical order
move attributes of v3.client.Client into alphabetical order

Just make self.users be consistent with the other assignments.

Change-Id: Ib3053774e9dd905eb4ef50668d6638ce19750177

sdpp/python-keystoneclient,Mercador/python-keystoneclient,klmitch/python-keystoneclient,alexpilotti/python-keystoneclient,Mercador/python-keystoneclient,darren-wang/ksc,magic0704/python-keystoneclient,ging/python-keystoneclient,ging/python-keystoneclient,sdpp/python-keystoneclient,alexpilotti/python-keystoneclient,magic0704/python-keystoneclient,klmitch/python-keystoneclient,darren-wang/ksc