Fetch all Meetup group events using GET /events endpoint.

Fixes #60
Merge branch 'get-all-events-in-meetup-group' of github.com:webuildsg/webuild into github/get-all-events-in-meetup-group
amended formatted_date and sorting of events by year
Merge pull request #62 from webuildsg/get-all-events-in-meetup-group

Fetch all Meetup group events using GET /events endpoint