Refactor event object

- Stop using Virtus for event model. It was causing coercion and
  validation hell. Now being a lot more strict with our object models.
- Add ipv4/fqdn observable collections
- Add validations for type checking
Add URL support
Update CSV parser to include URLs
Merge pull request #92 from justfalter/fixup_model_and_add_urls

Fixup model and add urls