AUTO-1036 Add a workflow file to this repo (non functional change) #patch

[sgopsbot]

This PR will add in a workflow.json file. Merging this into your repo will have no functional change, you can merge this in now - and merge in the updates to your versioning at your convenience later. What this PR will give you, is a standard for us to build upon, and the ability for the bots to know which job in Jenkins to kick off when you merge your PR in. Your jobs will still poll for changes to master - but some of them are on 20 minute timers. If you merge your PRs using the bots, they can trigger builds right away, removing 20 minutes from your wait. This also paves the way for us to get your PRs into staging without needing to merge into master.

This is a non-functional change, and should have no impact on your apps' functionality. It also probably does not need a version bump / changelog bump, as it does not need to be deployed and can just carry along w/ other changes.

Here's what you need to do:

• Verify that you need chef-data updates. If you need mesos-jobs updates instead, see https://github.com/sendgrid-ops/opsbot/blob/master/workflow.json for an example on how to put in the mesos-jobs keys
• If your repo does not use chef-data or mesos-jobs, you should ping Autobots for how to get incorporated into there, if there's a good reason to be outside of our version control system, then remove the envrepo, staging, and production settings.
• Verify in chef-data that your key uses sendgrid-swagger. If it does not, update the PR to reflect what it does use.
• Verify in chef-data that your key uses revision. If it does not, update the PR to reflect what it does use.
• Verify in Jenkins that sendgrid-swagger is the name of your master job. If it is not, update the PR to reflect the actual name.
• Verify in Jenkins that sendgrid-swagger-pullrequests is the name of your PR job. If it is not, update the PR to reflect the actual name.

To learn more about what the workflow.json file contains, check here: https://wiki.sendgrid.net/display/ES/Automated+Workflow#AutomatedWorkflow-UpdatestotheRepoitself:
(this could be merged in on red - but that's up to you and your team)