WL-2901 Don't display hidden courses in search.

We also updated the code for hidden courses and add a permission check to the call that hides a course so that only a course administrator can hide a course.
Add license to files.
Get the framework to convert to Boolean.
Add some more JavaDoc about hiding courses.
Make sure we re-index the course when we (un)hide.

Now that the hidden flag is in the index we need to re-index when changing it.
Remove security check as service does this.

Now the service checks if the user has permission to hide the course so we don't need the extra check in the JAX-RS code.
Correct language in JavaDoc.
Merge pull request #109 from ox-it/WL-2901

WL-2901 Don't display hidden courses in search.