tempest job as default for node_prepare

Change-Id: I9e9bff6adbd9019df6c389d3d70a49d5735a75db
modify creating venv

Change-Id: Ieec9f9015f511ccc6065e7a2be005f4fc357c4d1
tempest.cli nova_manage tests skipped because it can runs only on controller

Change-Id: I5be2792f7ec82124122f95ab9d1d1b438d2a7caf
creating of symlinks for OS clients  in /usr/local/bin implemented

Change-Id: I9a124af194750009f68472bc7a7fb1fcc804a447
skip object_storage tests - swift is not supported

Change-Id: I8a337ae499c1904a96f7d57b82087058949efb67
fix autodetection of cluster config via nailgun for fuel-4

Change-Id: Id9f2882c441ea200ef66acaeee22662705d4c6d8