Fix router params schema validation

[nicck]

To use latest node-framework in hotelier these fixes needed:

• it's not rare then we want to validate parameter format (uuid, date, etc)
• preprocessed schemas may have optional parameter

Other observations:

• we still have required for QueryParam, may be we should try to unify DSL for schema definitions
• a bit strange to not see warning on @QueryParam('nights', { schema: { type: 'integer', min: 1 } }) (should be minimum)
• example keyword considered invalid now