Resolve "Don't log query strings"

GitLab Pages does nothing with query strings, but JS hosted on pages may demand tokens or other credentials to be present in them. To be safe, we should avoid logging them at all.

Log output before this change:

# logging.go change:
group.gitlab-example.com 127.0.0.1:45324 - - [2018-03-26 17:58:43.93857839 +0100 BST] "GET /foo?token=bar HTTP/1.1" 404 3067 "https://example.com/foo?token=bar" "curl/7.52.1" 0.000470

And after:

group.gitlab-example.com 127.0.0.1:45342 - - [2018-03-26 17:59:21.197902047 +0100 BST m=+1.719440391] "GET /foo HTTP/1.1" 404 3067 "https://example.com/foo" "curl/7.52.1" 0.000303

Note that we strip them out of both the request URI and the referer URI.

Closes #116 (closed)