test: make print calls compatible with Python 3.x

In a Python 3 'print' becomes a function, see [1].
Patch makes print calls compatible with Python 3.

1. https://docs.python.org/3/whatsnew/3.0.html#print-is-a-function

Author: ligurio

test/cluster-py/multi.test.py

@@ -18,11 +18,11 @@
 def check_connection(con):
     try:
         s = con.space('test')
-        print s.select()
+        print(s.select())
     except NetworkError:
-        print 'NetworkError !'
+        print('NetworkError !')
     except Exception as e:
-        print e
+        print(e)
 
 
 # Start instances