Save endpoint schema on generation

[metanoic]

When generating from a live device schema, also fetch the firmware versions and archive the json payload along with the firmware versions so that we have an archive of CRC's that can be used to skip the schema fetch on device connection.

[metanoic]

On second thought we probably don't need to store the firmware versions as we can just test against a non-zero endpoint with the supplied CRC and if it works, then it must match. Maybe just use a real short timeout on that test/investigation request.

[metanoic]

We'll be adding a new endpoint for exposing the json schema CRC without needing to know it ahead of time. So let's just save the schemas keyed by the CRC.