contrib/fast-import: use a lowercase "usage:" string

Make the usage string consistent with Git.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/fast-import/git-import.perl

@@ -7,7 +7,7 @@
 use strict;
 use File::Find;
 
-my $USAGE = 'Usage: git-import branch import-message';
+my $USAGE = 'usage: git-import branch import-message';
 my $branch = shift or die "$USAGE\n";
 my $message = shift or die "$USAGE\n";
 

contrib/fast-import/git-import.sh

@@ -5,7 +5,7 @@
 # but is meant to be a simple fast-import example.
 
 if [ -z "$1" -o -z "$2" ]; then
-	echo "Usage: git-import branch import-message"
+	echo "usage: git-import branch import-message"
 	exit 1
 fi
 

contrib/fast-import/import-zips.py

@@ -19,7 +19,7 @@
         sys.exit(1)
 
 if len(argv) < 2:
-	print 'Usage:', argv[0], '<zipfile>...'
+        print 'usage:', argv[0], '<zipfile>...'
 	exit(1)
 
 branch_ref = 'refs/heads/import-zips'