Automatic discovery of TripleO Overcloud hardware

-geting IP addresses from Undercloud nova, allowing
 to poll all Overcloud nodes via SNMP
-adding support of basic auth, user_name and password
 used in TripleO by default

Change-Id: I189dbba9579055c8a1a878a769760a72e9174c6d
Merge "Automatic discovery of TripleO Overcloud hardware"