Update validator to 3.4.0

Closes #1379

- Convert to new api usage for both server-side and client-side
- Provide way require a negative response for boolean methods in
  default-settings.json
- Add field validation functional tests
  - Settings (General)
    - Title length validation
    - Description length validation
    - postsPerPage, numeric, min, max
  - Settings (User)
    - Bio Length validation
    - Location length validation
    - Url validation
  - Login
    - Email validation
  - Editor
    - Title required validation
Merge pull request #2286 from jondavidjohn/validator-upgrade

Update validator to 3.4.0