Set autocomplete="off" on the search bar

[fedarko]

This is a minor issue, but when using the node search bar Chrome attempts to be helpful and tries to show autocomplete options -- this gets in the way of the autocomplete menu that Empress already shows:

From https://gist.github.com/niksumeiko/360164708c3b326bd1c8, it looks like using autocomplete="off" on the search bar <input> hides the browser's autocomplete from popping up, letting Empress' actually useful autocomplete be shown.