upgrade to librabbitmq 0.4.1 so RabbitMQ2 support

yo, since this doesn't work on rabbitmq 1.7.2+, I've patched it up, which consists of

 * removed the fork of librabbitmq and replaced it with a git submodule and symlinks
 * version bump to 0.3.0 and a note about backwards compatibility
 * now works with new rabbitmq, but since the library is amqp protocol version 0.9.1 only rabbitmq2+
 * i had to remove the basic_return callback, since hacking up a library file is wrong, it should probably be pushed upstream and if the changes are accepted then the feature added back in
 * changed Changes file to be CPAN::Spec parsable
 * other things, i forget what.

If you like it, merge it and release it. if you don't, I'll probably fork it off into the Net::RabbitMQ2 namespace. If i don't hear back from you I'll assume it's abandoned and add a note and do a release + future maintenance 

Either way it's all good. Thanks for doing all the groundwork, i only patched it up and that was hard enough :)