Fixed ./bin/django-ember-precompile so that it can be executed

Apparently, if the shebang contains a \r it will prevent
that script from executing correctly using `/usr/bin/env node`

I pulled this down and noticed that in zsh I was getting this error:

    env: node\r: No such file or directory

Here is how you can play around to see this bug in action:

    vim bin/django-ember-precompile
    :set ff

Then you should see something like

    fileformat=dos

And try to run the command (from vim):

    :!./bin/django-ember-precompile

You should see something along these lines:

    env: node\r: No such file or directory

Then if you change that to unix and save the file:

    :set ff=unix
    :w

And run it again:

    :!./bin/django-ember-precompile

You should see this:

    USAGE: node django-ember-precompile filepath

SUCCESS!!!