Addresses PR #215 by changing the default behavior of the Netty InboundHandler to attempt to pass the Netty ByteBuf directly to the connection without first turning it into a reactor.io.Buffer.

This makes it possible to use the low-level Netty buffer manipulation methods and pooling in Stream Consumers.
Merge remote-tracking branch 'origin/direct-bytebuf'
Remove the unnecessary Afterburner Jackson module.
Refactor the Codec classes from reactor-tcp to reactor-core.

Previously, since the Codec class and standard implementations were only in the TCP submodule, other code like the PersistentQueue abstractions had to have their own versions of Codec and family. This change refactors the Codecs from reactor.tcp.encoding into reactor.io.encoding in reactor-core and standardizes other uses of Codec onto this single, shared Codec abstraction.
Merge branch 'move-codec'