contrib/git-svn: allow --authors-file to be specified
contrib/git-svn: allow --authors-file to be specified

Syntax is compatible with git-svnimport and git-cvsimport:

	normalperson = Eric Wong <8c2951295f8292b0c03727bc4652981172298eae@yhbt.net>

If this option is specified and git-svn encounters an SVN
committer name that it cannot parse, it git-svn will abort.

Signed-off-by: Eric Wong <8c2951295f8292b0c03727bc4652981172298eae@yhbt.net>
Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git