Include what was changed in notification email

[aslakknutsen]

For WorkItem Update and Comment Update notifications, only part of the new state is included. In the Work Item Update case the email is a notification that 'something changed', but with no real information to what.

The current UX can be found here: https://redhat.invisionapp.com/share/XHD0O8A5B#/248448905_Notification-Comment-Updated

• Expose Work Item revision API Expose Work Item revision API fabric8-services/fabric8-wit#841
• Expose Comment revision API Expose Comment revision API #1989
• Use 'what has changed' API for comments/workitem Use 'what has changed' API for comments/workitem fabric8-services/fabric8-notification#11

Related

• Provide audit history for all workitems Activity History #290
• Activity History Provide audit history for all workitems #1468

[surajssd]

• Now WIT sends revisionID along with the workitemId to notification service. send revisionid to notification service fabric8-services/fabric8-wit#2176

• What notification service can now do is parse this revisionID from the custom attributes and in order to generate workitem update template it should query the WIT endpoint GET /workitems/{wiID}/events. And in the output you will get all the events and here notification service should filter on the basis of revisionID sent earlier by WIT. This particular revision info can help generate updated template.

[joshuawilson]

How much of this is left to do? I know some improvements have been made.
cc @alexeykazakov