message: When hitting "tab" use an autocompleteDelay of 0
  So that there's no delay when tab completing. Fixes
diff: @@ -68,7 +68,7 @@ export default class Autocomplete extends React.Component {
  let autocompleteDelay = UserSettingsStore.getLocalSetting('autocompleteDelay', 200);
  // Don't debounce if we are already showing completions
  - if (this.state.completions.length > 0) {
  + if (this.state.completions.length > 0 || this.state.forceComplete) {
  autocompleteDelay = 0;
  }
  