Adds jicofo install instructions.

* in the example code for config.js in INSTALL.md
  contains three key-value-pairs not present in the example file
  'config.js.example' - these were appended without inserting a comma
  and the last two of these were commented out without removing
  the trailing comma - the example file 'config.js.example' is correct
  but using the INSTALL.md version causes the page render to halt prematurely
  making login impossible

Don't  use the prosody admin console, as it's disabled.

If `lsb-release` is not installed, an invalid entry is added to `/etc/apt/sources.list`, leaving apt in an unusable state

Applies Fcrancois's suggestion about tipping users where they can start testing.
Removes occurrences of jitmeet since the name is no longer in use.

Change some jitmeet references to Jitsi Meet and other minor cleanup.