Set socket timeout for SSH keyscan

When we switch from paramiko client to paramiko transport we failed to
properly setup a timeout.

Change-Id: Ia25c7f31a55d0d6e6bd42b2b266f41a4a2daf8ba
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

nodepool/nodeutils.py

@@ -68,6 +68,7 @@ def keyscan(ip, timeout=60):
         t = None
         try:
             sock = socket.socket(family, socket.SOCK_STREAM)
+            sock.settimeout(timeout)
             sock.connect(sockaddr)
             t = paramiko.transport.Transport(sock)
             t.start_client()