Handle InstanceUserDataMalformed in create server v2 api

The following patch adds missing support for handling
InstanceUserDataMalformed. In addition, it also adds test cases
in both the v2 and v3 api.

Change-Id: I1b474318248f64eed994f67c6d91db38d5579a63
Closes-bug: #1257146
Merge "Handle InstanceUserDataMalformed in create server v2 api"