Fix 'os-interface' resource name for Nova V2.1

V2 and V3 diff for this resource name is below-
V2 - '/servers/os-interface'
V3 - '/servers/os-attach-interfaces'

V3 resource name needs to be changed to work that for V2.1

Change-Id: I37bd7cee7e8879b01a8aee739d74c2dd6e033dc4
Closes-Bug: #1368035
Give context to the warning in _sync_power_states

The "Found x in the database and y on the hypervisor"
warning in the logs doesn't give any context to what
is happening when that is logged, this adds the context.

Change-Id: I8800006508b2e18de657aa0a8d135bcd17cb89f1
Fix Typo in method name - parse_Dom

Silly typo

Closes-Bug: #1374158

Change-Id: Icccfb1a606bc9e14188d9f5c5f5667e35f2cb413
Merge "Give context to the warning in _sync_power_states"
Merge "Fix 'os-interface' resource name for Nova V2.1"
Merge "Fix Typo in method name - parse_Dom"