Preparing release 1.1.0.

#### Changelog 1.1.0-alpha
- Added the constraints boolean, isArray and keyExists
- Added the constraint notEmptyKey and completed the issue #4
- Added the constraints object, instance and notInstance. Added too the method getValidation to Validator for get a single violation message based on id
- Added a new constraint: date
- Added the custom constraint registration feature from issue #11