Fix bugs in old HTTP API

This MR fixes bugs introduced by b18320c0 that render the old HTTP API (deprecated, but still used by GWpy and others) broken.

Closes #19 (closed).

changed milestone to %GWDataFind Client 1.1.1

added apipatch label

requested review from @duncan.meacher

assigned to @duncan.meacher

approved this merge request

merged

mentioned in commit 4d109a54