Feature/tags

This PR adds tags support at POST /v1/tags

It doesn't have related tags yet.
Tests are now idempotent and run faster than reviously.
This PR subsumes an earlier one in which the application context was refactored some, and configured to run the static browser application.

In this PR, You'll find that the XQuery search response transform is in use, to avoid the open transactions issue caused by JavaScript.  This should make this update more workable, by not being exposed to the outstanding bug server-side.