Implement support for some basic embed options for work sheets via LTI

This commit also fixes an issue with the flash messages being positioned too high and displayed for too long

app/controllers/request_for_comments_controller.rb

@@ -96,6 +96,10 @@ class RequestForCommentsController < ApplicationController
   # POST /request_for_comments
   # POST /request_for_comments.json
   def create
+    # Consider all requests as JSON
+    request.format = 'json'
+    raise Pundit::NotAuthorizedError if @embed_options[:disable_rfc]
+
     @request_for_comment = RequestForComment.new(request_for_comment_params)
     respond_to do |format|
       if @request_for_comment.save