Upgrades, added keystone authorization

* extracted generation of endpoints data
  to separate method
* use credentials from astute config
  if they are exist
* added keystone authorization for
  nailgun client

Change-Id: I3ae57e2352a16a35799e6c8e855c6a03bc2259ad
Closes-bug: #1342045
Merge "Upgrades, added keystone authorization"