Add support for triggering slots

For the moment, this can only fetch the slots configuration from the LHCbNightlyConf project, resolve branches and merge requests and display the JSON dictionaries.

We need to:

• create the documents in the database (which one?)
  • new db only
  • when triggering slots from the old system we have id clashes
• trigger the builds (which system?)
• (optional) open a window with the slots just started
  • requires a view that can display a specific list of slots
• basic authentication?
• allow custom (one off) slots?