Remove Support for VixDiskLib 5.1.0

VixDiskLib 5.1.0 has a known bug intermittently causing a
segfault during disk open operations when the vCenter Server
does not provide an SSL thumbprint for the target host.  The
code has been modified to allow unsupported versions to be
specified in the "bad_versions" array.

@roliveri @jrafanie @chessbyte please review.
I think using "include?" instead if "index" may make this easier to read.