Override #pretty method to set custom html template
Override #pretty method to set custom html template

This overrides Rack::ShowExceptions::TEMPLATE without affecting other
Rack apps that are mounted alongside Sinatra.

jkowens/sinatra,JonMidhir/sinatra,ryanshaw/sinatra,jkowens/sinatra,JonMidhir/sinatra,sinatra/sinatra,sinatra/sinatra,ryanshaw/sinatra,jkowens/sinatra,JonMidhir/sinatra