Fix Emacs plugin

With Emacs 24.3 on Mac OS X the command `emacsclient --alternate-editor '' --eval '(x-display-list)' 2>/dev/null` returns `nil`, what makes absolutely sense from a LISP point of view, but breaks the script.

### What went wrong before?

The `e` alias from the plugin triggered a start of Emacs server as expected, but since `nil` was returned, the `--create-frame` option was not provided. Without an existing open frame / window, this results in opening Emacs client in the terminal. Since the alias adds the `--no-wait` option, the Emacs client in the terminal was immediately closed again. The user might think, Emacs is crashing 😉.