[PATCH] Make svn clients indicate their operation name to backend(right now only to DAV)

Hi All,

This patch is with respect to the original thread

http://mail-archives.apache.org/mod_mbox/subversion-dev/201001.mbox/browser

Once this patch gets committed I can commit the mod_dav_svn change to
handle the original commit via outdated proxy issue.

This Patch revs the following public APIs,

'svn_client_uuid_from_url', 'svn_client_open_ra_session' and 'svn_ra_open3'.

For ra_neon and ra_serf layers it sets the http client header SVN-ACTION
with the concerned svn command name.

With & Without this patch mergeinfo_test-8 fails both over ra_neon and
ra_serf.

If there are no objections I will commit this change in next 2 days.

With regards
Kamesh Jayachandran