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/controllers2.py

@@ -15,46 +15,46 @@ the Mininet() constructor.
 from mininet.net import Mininet
 from mininet.node import Controller, OVSSwitch
 from mininet.cli import CLI
-from mininet.log import setLogLevel
+from mininet.log import setLogLevel, info
 
 def multiControllerNet():
     "Create a network from semi-scratch with multiple controllers."
 
     net = Mininet( controller=Controller, switch=OVSSwitch )
 
-    print( "*** Creating (reference) controllers" )
+    info( "*** Creating (reference) controllers\n" )
     c1 = net.addController( 'c1', port=6633 )
     c2 = net.addController( 'c2', port=6634 )
 
-    print( "*** Creating switches" )
+    info( "*** Creating switches\n" )
     s1 = net.addSwitch( 's1' )
     s2 = net.addSwitch( 's2' )
 
-    print( "*** Creating hosts" )
+    info( "*** Creating hosts\n" )
     hosts1 = [ net.addHost( 'h%d' % n ) for n in ( 3, 4 ) ]
     hosts2 = [ net.addHost( 'h%d' % n ) for n in ( 5, 6 ) ]
 
-    print( "*** Creating links" )
+    info( "*** Creating links\n" )
     for h in hosts1:
         net.addLink( s1, h )
     for h in hosts2:
         net.addLink( s2, h )
     net.addLink( s1, s2 )
 
-    print( "*** Starting network" )
+    info( "*** Starting network\n" )
     net.build()
     c1.start()
     c2.start()
     s1.start( [ c1 ] )
     s2.start( [ c2 ] )
 
-    print( "*** Testing network" )
+    info( "*** Testing network\n" )
     net.pingAll()
 
-    print( "*** Running CLI" )
+    info( "*** Running CLI\n" )
     CLI( net )
 
-    print( "*** Stopping network" )
+    info( "*** Stopping network\n" )
     net.stop()
 
 if __name__ == '__main__':