python/samba: Add some compatability PY2/PY3 functions

I hope these changes are a short term interim solution for the
absence of the 'six' module/library. I also hope that soon this
module can be removed and be replaced by usage of six.

Signed-off-by: Noel Power <noel.power@suse.com>
Reviewed-by: Alexander Bokovoy <ab@samba.org>

python/samba/compat.py

@@ -22,8 +22,20 @@ import sys
 PY3 = sys.version_info[0] == 3
 
 if PY3:
+    # compat functions
+    from  urllib.parse import quote as urllib_quote
+    from urllib.request import urlopen as urllib_urlopen
+
+    # compat types
     integer_types = int,
+    string_types = str
     text_type = str
 else:
+    # compat functions
+    from urllib import quote as urllib_quote
+    from urllib import urlopen as urllib_urlopen
+
+    # compat types
     integer_types = (int, long)
+    string_types = basestring
     text_type = unicode