GET /contacts/by_kshema_id responds with 404 if contact not found
[#70971930] except was not working ok.
[#70971930]improve select -> mode convertion
Merge 70971930-attributes-bug to master

[Completes #70971930]
[#70592222]last_seen_at as LUA
Merge 70592222-last_seen_at to master

[Completes #70592222]
[#70592222] Add last_seen_at to ContactSerializer
[#70592222] Parse last_seen_at param as Date before updating attribute
[#64751132 a
[#70592222] Add last_seen_at as search parameter
[#70592222] parse last_seen_at param on search
fix condition
[#70592222] heroku handles the params keys without symbolizing them, so last_seen_at was being stored as a regular attribute instead of a LUA