Fail CircleCI builds when "automated" fields in manifest.json are changed

[nareddyt]

Some fields in manifest.json are "automated", meaning they are actually set by CircleCI during Continuous Deployment. Those fields should never manually be changed by developers, as CircleCI will always set them to the correct value.

List of "automated" fields in manifest.json:

• version
• version_name
• icons

Perhaps we should make a bash script to ensure these fields are set to their defaults. Then, we can run this inside the CircleCI build step, failing the build if a developer changes these "automated" fields.