debloat: remove vsphere, kubes, aerospike -> half rss, half binary size

Printing --help now takes less than half the rss, and takes less than
half the time, the x64 binary is also half the size.

Stuff like discovery should probably get split out into it's own binary,
and/or things like this should get build-tagged imports so that they can
be exluded by people who have no need for them.

I'm sympathetic to the challenges of writing
serialization/deserialization code in Go, but the bloat from reflect
retention and the need for init() based planning causes a lot of
overhead for unused features.