Create booking system

[varenius]

A booking system is needed to avoid conflicts of telescope usage. Some desired features:

• [ ] Access the system with a personal account (created in the system, or via e.g. Google auth or similar)
• [ ] Book sessions (start/end maybe rounded to 15 minutes?) to observe with one or more telescopes
• [ ] Telescope access limited to the booked time, and UI aware of this (e.g. session time left)
• [ ] All times in UTC (to start with) and possibly localised timeszones (later)
• [ ] Language aware (select in profile should alter language for full system, including booking system)

[freidrichen]

I'm having a go at this, but my time is quite limited. If someone else feels like they would like this to move faster, just tell me and we can split up the work between us.