[Libguestfs] v2v: Remove --no-trim, --vmtype options and other fixes.

The first two patches implement the change discussed here: https://www.redhat.com/archives/libguestfs/2016-April/msg00178.html The third patch fixes the mapping of inspection data to OVF VmType which was inherited directly from old virt-v2v and had never been changed. It had a number of problems. The fourth patch is only slightly related to the others. It adds an extra slow test to ensure that trimming doesn't regress, fixing https://bugzilla.redhat.com/show_bug.cgi?id=1264332 Rich.