WIP: Added tinymce editor on course overview

This PR added tinymce editor on overview course in CMS course settings, it includes code plugin in tinymce to allow edit code.
![captura de pantalla de 2014-10-16 14 23 47](https://cloud.githubusercontent.com/assets/31282/4669008/22cb675a-556a-11e4-89a6-e4697b85f193.png)
![captura de pantalla de 2014-10-16 14 23 34](https://cloud.githubusercontent.com/assets/31282/4669015/301137fa-556a-11e4-81bb-a5f466ddf0c8.png)


If you're going to be using the tinymce library, then you should make sure that the variable is bound correctly in the `define()` call. I'd suggest doing something like this:
```js
 define(["js/views/validation", "codemirror", "tinymce", "underscore", "jquery", "jquery.ui", "js/utils/date_utils", "js/models/uploads",
    "js/views/uploads", "js/utils/change_on_enter", "jquery.timepicker", "jquery.tinymce", "date"],
     function(ValidatingView, CodeMirror, tinymce, _, $, ui, DateUtils, FileUploadModel, FileUploadDialog, TriggerChangeEventOnEnter) {
```
Notice how the `tinymce` variable now included in the parameters of the function definition, so that it lines up with the `"tinymce"` string in the list of dependencies. Require.js will ensure that the `tinymce` variable is bound to the contents of the tinymce library.