Upgrade to cirros 0.3.2

Cirros 0.3.2 is fixing the host name setting issue, which
is required for turning on the tempest instance validation tests.

Change-Id: I1b87740ab02c4eb0a8df653a35e1f85d40abda51
Related-Bug: #1132686
Merge "Upgrade to cirros 0.3.2"