add disabled property for Input components

Author: kroepke

src/Input.jsx

@@ -23,7 +23,8 @@ var Input = React.createClass({
     hasFeedback: React.PropTypes.bool,
     groupClassName: React.PropTypes.string,
     wrapperClassName: React.PropTypes.string,
-    labelClassName: React.PropTypes.string
+    labelClassName: React.PropTypes.string,
+    disabled: React.PropTypes.bool
   },
 
   getInputDOMNode: function () {

test/InputSpec.jsx

@@ -163,4 +163,13 @@ describe('Input', function () {
 
     assert.equal(instance.getChecked(), true);
   });
+
+  it('renders a disabled input correctly', function () {
+    var instance = ReactTestUtils.renderIntoDocument(
+      <Input type="text" disabled={true} />
+    );
+
+    var node = ReactTestUtils.findRenderedDOMComponentWithTag(instance, 'input').getDOMNode();
+    assert.isNotNull(node.getAttribute('disabled'));
+  });
 });