recipe/check_parameter: add support for Python 3 (NEEDS TO BE RELEASED BEFORE)

slapos/recipe/check_parameter/template/check_parameter.py.in

 #!%(python_path)s
 # BEWARE: This file is operated by slapgrid
 # BEWARE: It will be overwritten automatically
+from __future__ import print_function
 import socket
 import sys
 
@@ -9,9 +10,9 @@ expected = "%(expected-value)s"
 not_expected = "%(expected-not-value)s"
 
 if expected != "" and value != expected:
-  print "FAIL: %%s != %%s" %% (value, expected)
+  print("FAIL: %%s != %%s" %% (value, expected))
   sys.exit(127)
 
 if not_expected != "" and value == not_expected: 
-  print "FAIL: %%s == %%s" %% (value, not_expected)
+  print("FAIL: %%s == %%s" %% (value, not_expected))
   sys.exit(127)