Added Timeslice querying
Added Timeslice querying

with `start`, `end`, and `slice` query parameters, `/api/locations/{id}/count` can calculate multiple values over a section of time
    `start` and `end` must be ISO 8601 strings
    `slice` is the number of min that each slice will account for
    Time slices are paritioned from end to start, calculating only full slices; no partial slices are calculated at the start

Implemented a rejection system for alternate reasons, namely for a resource not existing reporting such a fact rather than a generic server error

LifoApp/lifo-server,LifoApp/lifo-server