feat(autocomplete): Submit form on enter

[MattKetmo]

Hello,

Is it possible that the autocomplete input acts like a standard input text when pressing the Enter key, to submit the form it belongs to?
I guess this behavior should only be enabled when the focus is on the input text and not on the suggestions.

What you think?

<form ng-submit="doSubmit(searchText)">
  <md-autocomplete md-search-text="searchText" md-items="item in getMatches(searchText)">
    <span md-highlight-text="searchText">{{item}}</span>
  </md-autocomplete>

  <md-button class="md-raised" type="submit">
    Submit
  </md-button>
</form>