Fix portability problem with #!/usr/bin/env (issue melpa#203)

Passing the 'script' option to emacs doesn't work as expected
on Linux, since the shebang is evaluated as:
  #!/usr/bin/env "emacs --script"

buildpkg

@@ -1,4 +1,5 @@
-#!/usr/bin/env emacs --script
+#!/bin/sh 
+:;exec emacs --script "$0" "$@"
 
 (add-to-list 'load-path (file-name-directory load-file-name))
 

migrate

@@ -1,4 +1,5 @@
-#!/usr/bin/env emacs --script
+#!/bin/sh 
+:;exec emacs --script "$0" "$@"
 
 (defun read-from-file (file-name)
   "read one lisp expression from a file"

missing.el

@@ -1,4 +1,5 @@
-#!/usr/bin/env emacs --script
+#!/bin/sh 
+:;exec emacs --script "$0" "$@"
 
 (defun difference (left right)
   "compare two lists"