[#15] Fix multiple replays, replacing pages_objects.{index => show}.

Replays were run multiple times, once per object, because each request
fetched the data for all objects (pages_objects.index). In addition,
much of the structure of unmoved.js was faulty.

Rewrote unmoved.js structure, retaining one request being sent per
object, but fetching data for that object only. Thus, replaced

    GET /pages/:page_id/objects

with

    GET /pages/:page_id/objects/:object_id

for both the server and unmoved.js.

Multiple requests were retained, to facilitate the possibility of
calling unmoved() on objects in stages, rather than all at once.
Merge branch 'bug/15-multiple-replays' into develop