Implement validation rules as per OASIS standard #7
Description
The OASIS standard describes a number of rules to validate the code list.
Such as this that applies to CanonicalUri, we need to implement a validation check in the canonical_uri.rb class:
Rule 4 [document] :
Must be an absolute URI, must not be relative.
The list of requirements:
oasis-reqs-implemented.md
oasis-requirements-1.0.md