print -> info; end the horror of print vs. print()

Although we could use print() from __future__, this messes
up scripts which use examples as modules.

The simple, if not nicest for 2.7, solution is to use
info(), output() and other mininet.log functions. The disadvantage
is that we may have to adjust things if we change info() to
add automatic newlines, but we can burn that bridge in Mininet
3.x.

examples/sshd.py

@@ -20,7 +20,7 @@ import sys
 
 from mininet.net import Mininet
 from mininet.cli import CLI
-from mininet.log import lg
+from mininet.log import lg, info
 from mininet.node import Node
 from mininet.topolib import TreeTopo
 from mininet.util import waitListening
@@ -60,17 +60,14 @@ def sshd( network, cmd='/usr/sbin/sshd', opts='-D',
     connectToRootNS( network, switch, ip, routes )
     for host in network.hosts:
         host.cmd( cmd + ' ' + opts + '&' )
-    print( "*** Waiting for ssh daemons to start" )
+    info( "*** Waiting for ssh daemons to start\n" )
     for server in network.hosts:
         waitListening( server=server, port=22, timeout=5 )
 
-    print()
-    print( "*** Hosts are running sshd at the following addresses:" )
-    print()
+    info( "\n*** Hosts are running sshd at the following addresses:\n" )
     for host in network.hosts:
-        print( host.name, host.IP() )
-    print()
-    print( "*** Type 'exit' or control-D to shut down network" )
+        info( host.name, host.IP(), '\n' )
+    info( "\n*** Type 'exit' or control-D to shut down network\n" )
     CLI( network )
     for host in network.hosts:
         host.cmd( 'kill %' + cmd )