Enable non-recursive autocomplete that accepts partial metric names

Building on https://github.com/wayfair/Graphite-Tattle/pull/48 (specifically, https://github.com/trbs/Graphite-Tattle/commit/fa4351de0959bed7bfdc44ececaeb088400eb465), make sure that if recursive autocomplete is turned off, users who enter partial metric/folder names are still able to see results if that partial name matches an actual metric key.