BUG-1568 Ssh Handler for netconf client Mina implementation

This implementation of Ssh Handler is asynchronous and based on Apache Mina SSHD.

+ Add Mina SSHD to distribution.

Change-Id: I51f51e2eb56b5f97a87c3d068ea90f8a44adca09
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>
Signed-off-by: Robert Varga <rovarga@cisco.com>