Correct attribution for casperd, co-sponsored by
The FreeBSD Foundation and Google, Inc.[1]

Since this was dual-sponsored, the sponsorurl needs
to be empty.

Add Google to the sponsor.ent file.

Reminded by:	rwatson [1]
Sponsored by:	The FreeBSD Foundation
Separate &darpa; entity and create &darpa_afrl to
avoid confusion.

Suggested by:	rwatson
Sponsored by:	The FreeBSD Foundation