Fix file validators, add new rules functions, update readme

Readme.md

@@ -155,11 +155,17 @@ ValidatorForm.addValidationRule('isPasswordMatch', (value) => {
     return true;
 });
 ````
-And remove them
+Get them
 ````javascript
-componentWillUnmount() {
-    ValidatorForm.removeValidationRule('isPasswordMatch');
-}
+ValidatorForm.getValidationRule('isPasswordMatch');
+````
+Remove them
+````javascript
+ValidatorForm.removeValidationRule('isPasswordMatch');
+````
+And check is validation rule already in list
+````javascript
+ValidatorForm.hasValidationRule('isPasswordMatch');
 ````
 
 ### API
@@ -175,13 +181,22 @@ componentWillUnmount() {
 | onError         | false    | function |               | Callback for form that fires when some of validations are not passed. It will return array of elements which not valid. |
 | debounceTime    | false    | number   | 0             | Debounce time for validation i.e. your validation will run after `debounceTime` ms when you stop changing your input |
 
-+ Methods
++ Instance methods (via ref)
 
 | Name             | Params | Return | Description                                        |
 |------------------|--------|--------|----------------------------------------------------|
 | resetValidations |        |        | Reset validation messages for all validated inputs |
 | isFormValid      | dryRun: bool (default true) | Promise   | Get form validation state in a Promise (`true` if whole form is valid). Run with `dryRun = false` to show validation errors on form |
 
++ Static methods (via class)
+
+| Name             | Params | Return | Description                                        |
+|------------------|--------|--------|----------------------------------------------------|
+| addValidationRule | name: string, callback: function |        | Add new validation rule |
+| getValidationRule | name: string | function | Get validation rule by name |
+| hasValidationRule | name: string | bool     | Check if rule exsits  |
+| removeValidationRule | name: string |       | Remove validation rule  |
+
 #### All validated fields (ValidatorComponent)
 
 + Props