Add support for rainbows dispatcher

Conflicts:
	lib/new_relic/agent/agent.rb
	lib/new_relic/local_environment.rb
Move rainbows before unicorn so it will be detected first since rainbows extends unicorn.

Conflicts:
	lib/new_relic/local_environment.rb
Sync rainbows detection logging with unicorn.
More unicorn/rainbows sync up.