Analyze netconf ssh client, fix FIXMEs, check for race conditions

Promote VirtualSocketException to checked exception, analyze how
2014-06-24 11:33:20.003 CEST [Thread-27] ERROR o.o.c.l.b.i.UncaughtExceptionPolicy - Thread Thread[Thread-27,10,main] died because of an uncaught exception
org.opendaylight.controller.netconf.nettyutil.handler.ssh.virtualsocket.VirtualSocketException: null
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.virtualsocket.VirtualSocket.getInetAddress(VirtualSocket.java:88) ~[na:na]
at ch.ethz.ssh2.Connection.<init>(Connection.java:68) ~[na:na]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.SshClient.connect(SshClient.java:48) ~[na:na]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.SshClient.openSession(SshClient.java:37) ~[na:na]
at org.opendaylight.controller.netconf.nettyutil.handler.ssh.client.SshClientAdapter.run(SshClientAdapter.java:57) ~[na:na]
at java.lang.Thread.run(Thread.java:724) ~[na:1.7.0_25]

happened before CONTROLLER-579