Merge branch 'dev' into master

This pull request implements course enrolment/unenrolment from the Preferences form, and makes some of the UI a bit nicer and more informative.

Each preference in config/prefsList.json now has an 'info' key so that preference options can be explained via tooltip. This improves accessibility to the system.

The admin dashboard UI has been improved. In particular:

• the main dashboard route has been made completely responsive by changing the massive .button-group into a two-row grid
• a bug fix for course creation is implemented which solves the inversion of 'code' and 'name' in the database
• the 'admin-remove-*' routes have an improved UI which uses custom toggle-switches as check-boxes instead of uk-close markers; this makes selections more clear on displays with poor colour reproduction