Policies, package dependencies and dynamic groups

Added

• Policy engine for device compliance. Policies are evaluated and enforced against devices, on top of the policy model itself. Deployments and device actions are logged as they run.
• Package dependencies. A package can declare what it needs, and the dependencies are resolved when a deployment or policy task runs. The agent installs them itself using the package manager the device has — brew, apt-get or yum — and a dependency can carry an installer URL.
• Dependency picker when creating a package. Dependencies are chosen from a dropdown while a package is being created.

Improved

• Agent enrollment and heartbeat behind a reverse proxy. Enrollment derives its base URL from the reverse proxy headers, and the URL is forced to HTTPS. The heartbeat uses an explicit SSL context and identifies itself with a User-Agent header.
• Agent configuration moved to a single JSON file. Enrollment, heartbeat and result posting all read their token and server URL from one configuration file instead of a set of environment variables, and they now validate that file and report what is wrong when it is incomplete.
• Serial number detection during enrollment. The method for reading a device's serial number during enrollment was reworked.
• Container builds and the production endpoint. FleetPilot is built and published as container images automatically, and the dashboard and the agent scripts point at the production endpoint.
• Deployments and device software views. Both screens got a pass over their interface, and detail views show a loading placeholder while data arrives.

Fixed

• The rules of a dynamic group were not evaluated. Rule evaluation now runs, and dynamic groups can be used as the target of a deployment or a policy like any other group.