ilom-snapshot: Use a single `-t`/`--type` option to set snapshot type.
Rename `idesl-get-ilom-address` to `ilom-address`.

Although the implementation is IDES-specific, we
need that command anywhere.  So, just add a note to
the top of the file that it should be customized
for everyone's environment.
ilom-address: Fix example in usage help text.
Renamed all `idesl-*` commands to `ides-*`.

As it turns out, IDES is the name of the cluster, and "idesl" is the
name of the login node.