Bring adapters out of preview

[garypretty]

Work is done, but preview flags need removing from the projects so the packages are not marked as pre-release anymore.

[cleemullins]

Pushing to R9 after discussion with Gary.

[garypretty]

Pushing to R10 as cleared with @cleemullins

[garypretty]

Facebook and Slack adapters now ready. Twilio / Webex adapters needs amending to accept the options class as opposed to the client class, mirroring the changes in Facebook.