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/submissions_controller.rb

@@ -129,6 +129,11 @@ class SubmissionsController < ApplicationController
     # end
 
     hijack do |tubesock|
+      if @embed_options[:disable_run]
+        kill_socket(tubesock)
+        return
+      end
+
       # probably add:
       # ensure
       #   #guarantee that the thread is releasing the DB connection after it is done
@@ -291,6 +296,11 @@ class SubmissionsController < ApplicationController
 
   def score
     hijack do |tubesock|
+      if @embed_options[:disable_score]
+        kill_socket(tubesock)
+        return
+      end
+
       Thread.new { EventMachine.run } unless EventMachine.reactor_running? && EventMachine.reactor_thread.alive?
       # tubesock is the socket to the client
 
@@ -308,6 +318,7 @@ class SubmissionsController < ApplicationController
   end
 
   def send_hints(tubesock, errors)
+    return if @embed_options[:disable_hints]
     errors = errors.to_a.uniq { |e| e.hint}
     errors.each do | error |
       tubesock.send_data JSON.dump({cmd: 'hint', hint: error.hint, description: error.error_template.description})