External validator function

Add the possibility to have an external validator function by passing to the validator an expression. Such as : "$validators" : { "equalsEmail" : "mustBeEqual(modelValue, 'email')" }

src/directives/schema-validate.directive.js

@@ -105,6 +105,17 @@ export default function(sfValidator, $parse, sfSelect, $interpolate) {
  // Check if our version of angular has validators, i.e. 1.3+
  if (form[attr] && ngModel[attr]) {
  angular.forEach(form[attr], function(fn, name) {
+ if ( angular.isString(fn) ) {
+ var fnName = fn;
+ fn = function( modelValue, viewValue, model, form ) { 
+ return scope.evalExpr( fnName, {
+ 'modelValue': modelValue, 
+ 'viewValue': viewValue,
+ 'model': model,
+ 'form': form
+ });
+ }
+ }
  ngModel[attr][name] = function(modelValue, viewValue) {
  return fn(modelValue, viewValue, scope.model, form);
  };