Missing tool_consumer_instance_guid parameter

[benbro]

The LTI request is missing the tool_consumer_instance_guid param.
This param is not required in the spec but recommended. It is useful in case you have several instances using the same LTI key and secret (dev/production, several campuses...).

Spec:

This is a unique identifier for the TC. A common practice is to use the DNS of the organization or the DNS of the TC instance. If the organization has multiple TC instances, then the best practice is to prefix the domain name with a locally unique identifier for the TC instance. This parameter is recommended.