Fail `schema-enforcer validate` when schema is not defined

[PhillSimonds]

When a data file is mapped to a schema ID which does not exist, rather than exiting with an error code of 1 and printing a failure message to the screen, schema-enforcer prints a message to the screen indicating that all schema validation checks have passed when the command schema-enforcer validate is run. The non-existent schema IDs still show up when the command schema-enforcer validate --show-checks is run. Functionality should be implemented in the tool such that:

• A log message is printed indicating that the referenced schema-id can not be found when the command schema-enforcer validate is run. The tool should also exit with a code of 1.
• The same should occur when the schema-enforcer validate --show-checks or schema-enforcer validate --show-pass commands are run.

[dgarros]

sounds like a bug to me :)