Fix bug: Wrong query to Update_Property

app/repositories/orient_db/learning_object_repository.rb

@@ -67,7 +67,7 @@ module OrientDb
 
     def update_property(learning_object,property,value)
       if accepted_properties.include? property
-        connection.command "UPDATE LearningObject SET #{property}=#{value} WHERE @rid = #{learning_object.id}"
+        connection.command "UPDATE LearningObject SET #{property}='#{value}' WHERE @rid = #{learning_object.id}"
       end
     end