Fix bug.

lib/roda/proxy.rb

@@ -158,6 +158,7 @@ class Roda
             .to_hash
             .reject { |k, v| k.downcase == 'transfer-encoding' } 
             .each { |k, v| response[k] = v.join("\n") }
+          response['Content-Type'] = response['content-type']
           # cookie = proxied_response['set-cookie'].to_s.split('; ').map{|s| k,v = s.split('='); [k, v.to_s]}.to_h
           # if cookie['_orbit_store_session']
           #   secret_key_base = YAML.load(File.read(File.expand_path("../../../../config/secrets.yml",__FILE__)))['production']['secret_key_base']