versionExchange: first stab in the dark
only send local version once
compare versions for compatibility
fixed Compatible and added a small test case
dont need coreos/semver yet
don't use my protobuf path
renamed version pkg to handshake
changed message from SemVer to Handshake1
addressed CR by @jbenet
Merge pull request #180 from cryptix/versionHandshake

Version handshake