Merge pull request #642 from cprice404/maint/burgundy/rename-count-query-param-again

Maint/burgundy/rename count query param again
Merge pull request #645 from cprice404/bug/burgundy/PE-1246-counts-shouldnt-be-nil

Bug/burgundy/pe 1246 counts shouldnt be nil
Merge pull request #644 from cprice404/feature/master/PE-1473-add-subject-key-to-event-counts-response

Change response format for subject of event-counts endpoint results
Merge pull request #643 from cprice404/bug/burgundy/PE-1393-bump-store-catalog-version

Retroactively add replace-catalog version 3
(PE-1345) move doc/clj files from experimental to v3

This commit moves various documentation and http endpoint files
from the `experimental` locations to the `v3` locations.  No
other changes are made in this commit, so that the actual
modifications will be easier to see in subsequent commits.
Update namespaces and URLs for new v3 endpoints