This commit improves a couple of things:
* All of the message templates are now at the top, a convention
we follow in a lot of our webhooks.
* Messages are not prefixed with any emojis. We don't do this in
any of our other webhooks. Plus, the emojis were outdated.
* Remove some superfluous code.
* Use ```quote <quote goes here> ``` style formatting for
quoted text instead of the `>` character.
This commit only adds support for the four events that have sample
payloads provided for them on the Pagerduty developer website.
Support for the remaining events will be added in subsequent
commits, as we get access to more sample payloads.
Eeshan Garg
Aditya Bansal
Tim Abbott
rht
Tomasz Kolek