Provide access to connection info (remote & local ports & addresses, protocols & protocol versions, etc)

[stupenrose]

Probably something like Request.connectionInfo()

[stupenrose]

As of bb7ffc3 & 81ca3af , this is mostly complete. The only thing remaining is the protocol & protocol version.

Regarding how to represent protocol & protocol version, it probably makes sense to wait until we have an opportunity to work with spdy & http 2.0 before making decisions.