Alias long to int under Python 3

In py3, the two types are unified under the name "int".

Reviewed-By: Tomas Babej <tbabej@redhat.com>

ipapython/install/cli.py

@@ -10,6 +10,8 @@ import collections
 import optparse
 import signal
 
+import six
+
 from ipapython import admintool, ipa_log_manager
 from ipapython.ipautil import CheckedIPAddress, private_ccache
 
@@ -17,6 +19,9 @@ from . import core, common
 
 __all__ = ['install_tool', 'uninstall_tool']
 
+if six.PY3:
+    long = int
+
 
 def install_tool(configurable_class, command_name, log_file_name,
                  positional_arguments=None, usage=None, debug_option=False,