packet v0.3.0 release
packet: version constraint for openflow.0.3.0

The latest version of packet is not compatible with openflow.0.3.0.
packet: update tarball checksum

The URL that points to the tarball involves a redirect. The previous
checksum was the checksum of the body of the redirect response body.
openflow v0.4.0 release
openflow: update version constraints for frenetic
Merge pull request #2248 from seliopou/packet

packet v0.3.0 and openflow v0.4.0 release