Add unit test to module `tables`

The unit test serves as a demonstration of how a unit test can be constructed
for almost any method in module `tables`. Also add a FIXME asking for more unit
tests to be written.
Make class names more consistent

For example: ensure that url /character/<id>/skills/update-form/ has a synonym
of `character-id-skills-update-form` and is handled by class
`CharacterIdSkillsUpdateForm`.