Bug 19678: Clicking Cancel when adding New Course to course reserves shows message...

Bug 19678: Clicking Cancel when adding New Course to course reserves shows message Invalid Course!

Clicking on the cancel link when adding a new course to course reserves
displays the message 'Invalid Course!'. It would be better if it
redirected back to the main Course Reserves page.

This patch redirects the user back to the main course reserves page.

To Test:

1. Go to Course Reserves

2. Click '+ New Course'

3. Cancel the process

4. You are shown 'Invalid Course!'

5. Apply patch and repeat steps 1-3

6. You are redirected back to the main course reserves page

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>