Move old keyword test files around

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Complete test structure for validation keywords

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>
Start test for AdditionalItems

All the basics are there for validation. Now on to equivalences!

Signed-off-by: Francis Galiegue <fgaliegue@gmail.com>