Added .focus() instance method

Author: the-spyke

src/Creatable.js

@@ -203,6 +203,10 @@ const Creatable = React.createClass({
 }
 },
 
+focus () {
+this.select.focus();
+},
+
 render () {
 const {
 newOptionCreator,

test/Creatable-test.js

@@ -237,4 +237,17 @@ describe('Creatable', () => {
 createControl({ onInputKeyDown: event => done() });
 return creatableInstance.onInputKeyDown({ keyCode: 97 });
 });
+
+describe('.focus()', () => {
+beforeEach(() => {
+createControl({});
+TestUtils.Simulate.blur(filterInputNode);
+});
+
+it('focuses the search input', () => {
+expect(filterInputNode, 'not to equal', document.activeElement);
+creatableInstance.focus();
+expect(filterInputNode, 'to equal', document.activeElement);
+});
+});
 });