ra_serf: Follow up r32417. Also add the DAV headers to the PROPFIND requests,  which ra_serf handles with specific code.
ra_serf: Follow up r32417. Also add the DAV headers to the PROPFIND requests, 
which ra_serf handles with specific code.

* subversion/libsvn_ra_serf/propfind_buckets.c
  (become_request): set DAV headers to inform the server of the client's
   capabilities.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion