Summary: KVM - double migration can fail

Detail: Undefine VM after migration. Lingering domain definitions cause
migrations back to the original host to fail, since domain already exists.

BUG-ID: CLOUDSTACK-2640
Bugfix-for: 4.1.0,4.2.0
Signed-off-by: Marcus Sorensen <marcus@betterservers.com> 1369285950 -0600