Better filetype detection

This takes a smarter approach to determining the file type so we don't barf all over the place when dealing with data that should be sent to shopify as binary data.

This fixes #85 

Please review @maartenvg 

/cc @jduff @tylerball 
Yeah I was running into some weird issues when trying to do it in the setup. I'll futz with this a bit more

- Chris / Developer @ Shopify

> On Jun 30, 2014, at 10:58, Maarten van Grootel <notifications@github.com> wrote:
> 
> In lib/shopify_theme/cli.rb:
> 
> > @@ -279,5 +284,9 @@ def show_during(message = '', quiet = false, &block)
> >      def timestamp(time = Time.now)
> >        time.strftime(TIMEFORMAT)
> >      end
> > +
> > +    def setupMimeMagic
> > +      MimeMagic.add('application/x-liquid', extensions: %w(liquid), parents: 'text/plain')
> Is this something we can do only once, instead each and every time a file is checked?
> 
> —
> Reply to this email directly or view it on GitHub.