git-svn: teach dcommit about svn auto-props

git-svn: teach dcommit about svn auto-props

Subversion repositories often require files to have properties such as
svn:mime-type and svn:eol-style set when they are added.  Users
typically set these properties automatically using the SVN auto-props
feature with 'svn add'.  This commit teaches dcommit to look at the user
SVN configuration and apply matching auto-props entries for files added
by a diff as it is applied to the SVN remote.

Signed-off-by: Brad King <brad.king@kitware.com>
Acked-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>