Merge pull request #12 from richardjh/master

Changed URL in README.md
Preparations for adding new 23rd meetup with new meetup fields
Added paragraph about speakers required
Merge pull request #13 from asgrim/meetup-entity-tweaks

Preparations for adding new 23rd meetup with new meetup fields
Merge pull request #14 from asgrim/speakers-required

Added paragraph about speakers required