Webform - Slack integration

Webform - Slack integration provides a Webform handler for posting a message to a slack channel when a submission is saved.

Dependencies

This module requires:

1. Webform, for providing the form functionality
2. Slack, for providing webhook integration. You will need to create an inbound webhook in your Slack team, and use this module to configure it within Drupal.

Remaining tasks

1. Allow 'default' as a channel selection, which will post to the channel set in the Slack configuration screen.
2. Implement SlackWebformHandler::getSummary().
3. Implement the 'Included message values' to allow better control over the [webform-submission:values] token.
4. Allow the username & icon to be configurable per form (again, providing default option).
5. If the Slack module develops, provide support for advanced formatting options: https://api.slack.com/incoming-webhooks#advanced_message_formatting.
6. Provide a default message?