Automagic attr_readers for ivars you set in Sinatra routes.

This lets us have Sinatra routes like this:

    get '/badge' do
      @job = Jobs::Job.first
      mustache :badge, :layout => false
    end

That work with a badge.mustache like this:

    {{# job}}
      <a class="job-link" href="{{url_with_host}}" target="_blank">
        <strong class="job-company">{{company}}</strong> is hiring a
        <strong class="job-title">{{title}}</strong> in
        <span class="job-location">{{location}}</span>
      </a>
    {{/ job}}

lib/mustache/sinatra.rb

@@ -88,6 +88,11 @@ def mustache(template, options={}, locals={})
         # Copy instance variables set in Sinatra to the view
         instance_variables.each do |name|
           instance.instance_variable_set(name, instance_variable_get(name))
+
+          # Automagic attr_readers for ivars you set in Sinatra routes.
+          if !instance.respond_to?(name)
+            (class << instance; self end).send(:attr_reader, name.to_s.sub('@',''))
+          end
         end
 
         # Render with locals.