change required check to exactly equal false

Author: Walker Leite

src/components/FormlyField.js

@@ -60,7 +60,7 @@ export default {
 
 	Object.keys(this.field.validators).forEach((validKey) => {
           if ( !this.form.$errors[this.field.key][validKey] ) this.$set(this.form.$errors[ this.field.key ], validKey, false);
-          if ( !this.field.required && !this.model[ this.field.key ] ) {
+          if ( this.field.required === false && !this.model[ this.field.key ] ) {
 	    setError(this.form, this.field.key, validKey, false );
 	    return resolve();
 	  }

test/unit/specs/FormlyField.spec.js

@@ -396,6 +396,7 @@ describe('FormlyField', () => {
           {
             key: 'search',
             type: 'test',
+            required: false,
             validators: {
               expression: 'field.value == "test"'
             }
@@ -446,6 +447,29 @@ describe('FormlyField', () => {
       },0);
     });
 
+    it('should run validators even if require does not exists and model is empty', done => {
+      let data = {
+        form: {
+          $valid: true,
+          $errors: {}
+        },
+        model: {
+          search: null
+        },
+        fields: [
+          {
+            key: 'search',
+            type: 'test',
+            validators: {
+              aValidator: () => done()
+            }
+          }
+        ]
+      };
+
+      createValidField(data);
+    })
+
     it('Async Validation', (done) => {
       let data = {
         form: {