adapt client to new Index API

This tries to address #1509,
with minimal implementation to adapt the client code to the new Index API.

I tried to reflect the new api name also in client code (IndexApi.js instead of TransitIndex.js) but we can also directly refactor the TransitIndex.js.
Get rid of several agencyId as new object identifiers already include it in the form <agId>:<objId>

Other changes should leverage on enhancements from the Api side, e.g.:
- routeList on Stop, to show in the popup
- pattern name, more concise than pattern description
- pattern on Trip, to avoid iterating on route patterns trips searching for wich pattern the trip belongs to
- findById and findByName endpoints (maybe /index/stops?name=abc*  or some other RESTFul uri)

but I think is worth waiting for the ongoing GTFS rework.

PS: the PR seems polluted by a lot of whitespace changes; this is due to my Atom editor which is trimming all whitespace line endings. sorry for that.