WIP: Generalise LBT to other events

[dnlburgess]

• Completely revised the database schema in preparation for new features (e.g. room authentication).
• Groups are now associated with a number of rooms, these can be added and deleted as required.

[matiasilva]

A very promising leap forward.

[dnlburgess]

Still to do:

• Implement links for groups and rooms (websites, social media etc)
• Implement authentication levels for rooms
• The room management page will have to be restyled to accommodate the above
• Rework other bits of styling (e.g. group logos on user home page)