Bug 1239 - Clean up and refactor netconf-ssh client

Remove commented and dead code in netconf-netty-util.
Move SshHandler to client package in order to make it package private.
Wrap OutputStream in SSHClientHandler with a buffer.
Remove VirtualSocketException as it was a workaround for
passing context without checking whether session was established.

Change-Id: I992d3b8ba2b2a58b69bd2e8be4ad0e4bdfa36c01
Signed-off-by: Tomas Olvecky <tolvecky@cisco.com>
Merge "Bug 1239 - Clean up and refactor netconf-ssh client"