Empty names are not allowed, and blueprint names should only contain
characters matching: ^[a-zA-Z0-9._-]+$
This also adds tests for the various places where the blueprint name
could potentially be wrong.
Also adds new types to weldr/json.go to support them.
ComposeEntry had to be duplicated instead of used as-is because it
enforces image type strings that do not match what the API uses (the API
types are all lower case, the internal names are capitalized).