Refactors google translate integration

Google Translate Widget Dropdown only display mode added in
https://github.com/codeforamerica/ohana-web-search/pull/540 appears to
have been inadvertently removed. This commit re-sets the dropdown mode
to dropdown only.
That will include an empty `<section id='language-box'><ul></ul></section>` ... I'd prefer to not include empty markup like that.