git-svn: add --username/commit-url options for branch/tag

Add ability to specify on the command line the username to perform the
operation as and the writable URL of the repository to perform it on.

[ew: shortened subject]

Signed-off-by: Igor Mironov <igor.a.mironov@gmail.com>
Acked-by: Eric Wong <normalperson@yhbt.net>

git-svn.perl

@@ -155,12 +155,16 @@ BEGIN
 	            { 'message|m=s' => \$_message,
 	              'destination|d=s' => \$_branch_dest,
 	              'dry-run|n' => \$_dry_run,
-		      'tag|t' => \$_tag } ],
+	              'tag|t' => \$_tag,
+	              'username=s' => \$Git::SVN::Prompt::_username,
+	              'commit-url=s' => \$_commit_url } ],
 	tag => [ sub { $_tag = 1; cmd_branch(@_) },
 	         'Create a tag in the SVN repository',
 	         { 'message|m=s' => \$_message,
 	           'destination|d=s' => \$_branch_dest,
-	           'dry-run|n' => \$_dry_run } ],
+	           'dry-run|n' => \$_dry_run,
+	           'username=s' => \$Git::SVN::Prompt::_username,
+	           'commit-url=s' => \$_commit_url } ],
 	'set-tree' => [ \&cmd_set_tree,
 	                "Set an SVN repository to a git tree-ish",
 			{ 'stdin' => \$_stdin, %cmt_opts, %fc_opts, } ],