(query, query)/*.js
-Remove unused `../src/logger` `require()`s.
src/logger.js, package.json
-Remove `src/logger` in favor of using `pelias-logger` for all
logging, since it's the Pelias standard.
middleware/500.js
-Replace usage of `src/logger` with pelias-logger.
query/sort.js
-Use the elasticsearch script introduced in
https://github.com/pelias/scripts/pull/7 to boost results with
exact text matches when documents' `_score`s are tied.
-Make `query/sort` export a function that creates the `sort`
query component, rather than the query component as a singleton,
to allow it to optionally add the exact-match script (that is,
when an `input` is present in `params`).