Incorporate the ColloCall Greenlight changes

The changes ColloCall have made to Greenlight allow the duration of meeting and the max number of users per room to be set per Greenlight container using Docker env vars, we should incproprate these changes into our Greenlight fork.

IRC logs:

16:13 < hng[m]> <chrisc "hng: I'd be interetsed in the URL"> 
                https://github.com/hng/greenlight/tree/feature/maxParticipants_duration
16:14 < hng[m]> You then set BIGBLUEBUTTON_MAX_PARTICIPANTS=25 for a limitation of 24 
                participants (BBB bug....)
16:17 < hng[m]> yes this branch also includes the code that adds the maxParticipants 
                setting to every create room api call
16:17 < hng[m]> this is the commit with the relevant code changes, if you interested to 
                know: 
https://github.com/hng/greenlight/commit/fd8efb539ae5ef31a7bc74eb57c959ea723e173d

Discourse post about this.