Creates and activates translator, editor and admin users.
protected function setupUsers() {
$this->translator = $this
->drupalCreateUser($this
->getTranslatorPermissions(), 'translator');
$this->editor = $this
->drupalCreateUser($this
->getEditorPermissions(), 'editor');
$this->administrator = $this
->drupalCreateUser(array_merge($this
->getEditorPermissions(), $this
->getTranslatorPermissions()), 'administrator');
$this
->drupalLogin($this->translator);
}