jsonschema provides a rich error tree of info, by parsing each error
we can pull out relevant info and re-write the error messages.
This covers current error handling behaviour.
This includes new error handling behaviour for types and formatting of
the ports field.
Signed-off-by: Mazz Mosley <mazz@houseofmnowster.com>
Define a schema that we can pass to jsonschema to validate against the
config a user has supplied. This will help catch a wide variety of common
errors that occur.
If the config does not pass schema validation then it raises an exception
and prints out human readable reasons.
Signed-off-by: Mazz Mosley <mazz@houseofmnowster.com>