VMware: fix image snapshot with attached volume

A snapshot of a instance with an attached volume will result in
the wrong volume being uploaded to glance. The reason for this
are as follows:
1. the last image in the list of images would be exported
2. the base image would not be exported but the first found

The same happens with a VM rescue if there is a cinder volume
attached.

The solution is to search for an image that contains the instance
UUID.

Change-Id: Ic85b0ffd4f1c34f10d07b1a198eaad2030803d6f
Closes-bug: #1243193
Merge "VMware: fix image snapshot with attached volume"