server: do not log mongo uri
server: support versioning in url

We prefer the /v1/mode/lat/lng/ style of API versioning over restify's
built-in support for it in the header.
erver: lat/lng pairs should be query params, not resource locators

The point of OpenMotion is that users are *searching* for transport
modes near their current GPS coordinates. So it makes more semantic
sense for the API to accept lat/lng pairs as query parameters, and
not as resource locators (which are misleading).

A benefit to this approach is that we can also support additional
arguments in the future, such as search radius, etc.
server: add support for all transport modes

Update our route to handle all supported transport modes.

Move mongoose schemas into separate module.
README: add some extra testing information