Bug 624 - Separate netty and exi specific classes from netconf-util.

As preparation step for splitting netconf into service and protocol,
create netconf-netty-util bundle with classes dependent on protocol
handlers - netty, exi, ssh.

Change-Id: I22ba17d0fa4f86c5f64cb3258a55f2c54da85dee
Signed-off-by: Tomas Olvecky <tolvecky@cisco.com>
Merge "Bug 624 - Separate netty and exi specific classes from netconf-util."