VMware: remove double import

"import mock" was done twice.

Change-Id: Ibc38d27d7fd8b57b193cbe37d2abd89b823ed43f
Add exception handling in "nova diagnostics"

when using "nova diagnostics" with a not running
instance, user will get an incorrect message. This
change handles that exception.

Change-Id: Ia2aa76a5c2c2aeed446411700d74d547dd73cf90
Closes-bug: #1289079
Merge "VMware: remove double import"
Merge "Add exception handling in "nova diagnostics""