Make the SVNAutoversioning command take an "on/off" argument, instead
just being present or not.  This allows us to set defaults within
locations, and override them in sub-locations.

* mod_dav_svn.c (dav_svn_cmds, dav_svn_autoversioning_cmd): make
  SVNAutoversioning take one boolean argument, not zero.  apache does
  the "on/off" parsing for us.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/autoversion@844320 13f79535-47bb-0310-9956-ffa450edef68