Fix duplicate caching of some templates
Fix duplicate caching of some templates

The change above makes sure that the `default_content_type` option is always deleted from the options.
This in turn makes sure that identical template is cached only once, regardless of whether the explicit `content_type` option is specified or not.
Not to mention it also makes sure that the `default_content_type` option is not passed as an engine option to the engine which might complain about it.
mwpastore/sinatra,ryanshaw/sinatra,burningTyger/sinatra,JonMidhir/sinatra,JonMidhir/sinatra,JonMidhir/sinatra,sinatra/sinatra,burningTyger/sinatra,mwpastore/sinatra,jkowens/sinatra,jkowens/sinatra,mwpastore/sinatra,burningTyger/sinatra,sinatra/sinatra,jkowens/sinatra,ryanshaw/sinatra