add Chinese locale translation "cn.json"

fix #160 validate on empty validation-service

merged PR #162 and PR #163

Merged #157 to add Simplified Chinese locale

Thanks to @wbiz for providing Simplified Chinese locale

update changelog

update changelog

Fix #150 angularValidation.revalidate problems

Thanks to @jsolt for fixing the issue

Fix disabled="false" as attribute to run validation

evaluate the disabled="false" attribute value in Angular-Validation so
that the validation kicks in when this value is set to "false". This was
problem found with the 3rd party library nya-bootstrap-select

Add silent mode to checkFormValidity function

Fix issue where empty Form Controller was throwing an error