Make script files executable automatically
You can force Emacs to make a file executable (respecting your
umask settings) if Emacs considers it a script. To determine if it is a script, Emacs will look for the hash-bang notation in the file and treat it as a script if it finds it.
Add this to your init file and Emacs will then make the file executable if it is a script.
(add-hook 'after-save-hook 'executable-make-buffer-file-executable-if-script-p)