Fix PendingDeprecationWarning about cgi.parse_qsl

I was running py.test based tests on a project which uses zodburi and
got many warnings:

	.../python2.7/site-packages/zodburi/resolvers.py:86: PendingDeprecationWarning: cgi.parse_qsl is deprecated, use urlparse.parse_qsl instead
	  kw = dict(parse_qsl(query))

Since for Python2 cig.parse_qsl was migrated to urlparse.parse_qsl in 2008:

	https://github.com/python/cpython/commit/c585df9476

it is safe to change to urlparse.parse_qsl unconditionally.

zodburi/_compat.py

 try:
     from urllib.parse import parse_qsl
 except ImportError: #pragma NO COVER
-    from cgi import parse_qsl
+    from urlparse import parse_qsl
 
 try:
     from urllib.parse import quote