Make the mod_dav_svn tests pass with Python 3 and ra-dav.
Make the mod_dav_svn tests pass with Python 3 and ra-dav.

* subversion/tests/cmdline/mod_dav_svn_tests.py
  (): Fix the httplib import for py3.
  (compare,
   compare_dict): Two new utilities b/c 'cmp' is not avaialble in py3.
  (compare_xml_elem): Use the new utils and portable sorting code.
  (cache_control_header,
   simple_propfind,
   propfind_multiple_props,
   propfind_404,
   propfind_allprop,
   propfind_propname): Conversion into base64 has bytes strings as input
                       and output.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1743594 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion