Avoid form submit for events meant to add chips (#102)

* Avoid form submit for events meant to add chips

This is mainly necessary for forms that contain a single ChipInput and nothing
else as the default behaviour for Enter is to submit the form:

    https://www.w3.org/MarkUp/html-spec/html-spec_8.html#SEC8.2

* Move form example to specific story

* add descriptive text to story

Author: nickcoutsos

src/ChipInput.js

@@ -147,6 +147,7 @@ class ChipInput extends React.Component {
     const handleKeyDown = this.autoComplete.handleKeyDown
     this.autoComplete.handleKeyDown = (event) => {
       if (this.props.newChipKeyCodes.indexOf(event.keyCode) >= 0) {
+        event.preventDefault()
         this.handleAddChip(event.target.value)
         this.autoComplete.setState({ searchText: '' })
         this.autoComplete.forceUpdate()

stories/index.js

@@ -205,3 +205,12 @@ storiesOf('ChipInput', module)
       addOnBlur
     />
   ))
+  .add('in a form', () => themed(
+    <form>
+      <ChipInput
+        onChange={action('onChange')}
+        floatingLabelText="This is a single chip input inside a <code>form</code>. Note that pressing Enter in the chip input does not submit the form."
+        fullWidth
+      />
+    </form>
+  ))