Restructure api and add event-status model

[toddapetersen]

This is a baseline restructure of the Agency api to address a number of endpoint changes and incorporate feedback received in previous issue and PRs (#161 , #116 and #63 ).

Major changes:

• provider_id is passed as part of an authorization bearer token.
• Looking up and registering vehicles use standard GET and POST operations on /vehicles endpoint.
• The /vehicles/{vehicle_id}/event allows Providers to POST events to affect vehicle status. The vehicle status is modeled around a state flow that is modeled in Vehicle Events table.
• Deregister vehicle, trip start and end are now events.
• Events for trip_enter and trip_leave were added to address trips that do not start or end in the Agency jurisdiction.

[HenriJ]

Hi @toddapetersen , love the more restful approach !

• Why send telemetry data in the {vehicle}/event endpoint instead of the /update_trip_telemetry (that could become a {vehicle}/telemetry) ? It might be interesting to be updated on the telemetry every 5 seconds (to keep up-to-date data on the battery level, ...).
• The Telemetry is referenced in the document, but I can't find the definition ?

[HenriJ]

Oops, just saw your PR #196 , it answers my questions :)

For the events, what should happen if the Agency server goes down ? Could we add a timestamp field the event so that if we receive it later, we can know the real time when it occurred ?

[hunterowens]

@toddapetersen

Couple things.

This PR needs to target the dev branch, not 0.2.x as it is breaking changes.

I noticed that #195 #196 #197 all target this branch rather than dev or 0.2.x and that is PR contains commits that should be in that are also in #195/#196/#197? Or do you have a different strategy to merge these commits? I think it is currently very unclear how changes are being made.

[hunterowens]

Need to additionally integrate rebase and integrate #172 before merging this.

[toddapetersen]

Discussed changes are committed and rebased against dev. Should be good to merge.