Go style calls for mixed caps instead of all caps:
https://golang.org/doc/effective_go.html#mixed-caps
Change LOOKUP, ACQUIRE, and RELEASE to Lookup, Acquire, and Release.
This vendors a fork of libnetwork for now, to deal with a cyclic
dependency issue. The change will be upstream to libnetwork once this is
merged.
Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>