Bind SshClient/SshServer to NettyIoServiceFactoryFactory
Our implementation are captives of SSHTransportStackFactory and
therefore should be bound to a particular EventLoopGroup and not delve
into DefaultIoServiceFactoryFactory's
getDefaultIoServiceFactoryFactoryInstance(), which works with
ServiceLoader.
Pass down NettyIoServiceFactoryFactory to make sure the configuration
does not stray from the path we have set for it.
JIRA: NETCONF-590
Change-Id: I32fc9115a28cb60cae1960293416a62a96529aec
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>