Move usage information printing to separate function, and print usage to stderr; also added some spacing.

(cherry picked from commit 17d274ef48)

qubes-rpc/qvm-run

@@ -20,8 +20,8 @@
 #
 #
 
-if [ $# -lt 2 ] ; then
-    cat <<USAGE
+function print_usage(){
+cat >&2 <<USAGE
 Usage: $0 vmname command arguments
 Executes a command in another VM using the qubes.VMShell RPC service.  The
 arguments are joined with spaces and passed to "bash -c".
@@ -33,10 +33,16 @@ is your terminal.
 
 You can use \$dispvm or --dispvm instead of vmname to start a new DisposableVM.
 USAGE
+}
+
+if [ $# -lt 2 ] ; then
+    print_usage
     exit 1
 fi
+
 VMNAME=$1
 shift
+
 if [ $VMNAME = "--dispvm" ] ; then
     VMNAME='$dispvm'
 fi