Add ConnectionContext

Used to track per-connection data, as opposed to RequestContext which is
per request.
Also move getRemoteAddress() from RequestContext to ConnectionContext (API breaking change).
Update dependency versions for release
[maven-release-plugin] prepare release nifty-parent-0.12.0
[maven-release-plugin] prepare for next development iteration
Add client-side security factory interface and no-op implementation
Stop deploying examples artifact
Add a TTransport that can wrap a NiftyClientChannel
Use an independent readerIndex when adapting a TTransport from a ChannelBuffer