BUG-1612 Implement mina ssh netconf server endpoint

Extract sessionCloseCallback and readHandler from AsyncSshHandlerReader

Change-Id: I0e09341fd59f74f7ac57688414a6dac7c9823b8a
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>
BUG-1612 Update netconf testtool to use new ssh server wrapper

Change-Id: I8625f8d34df65f6d7e47ad77d393f482afa1abdf
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>
Merge "BUG-1612 Implement mina ssh netconf server endpoint"
Merge "BUG-1612 Update netconf testtool to use new ssh server wrapper"