redesigning api, #43

redesigned the API to have:
* complete resource representations for both collection and member endpoints (prior design returned only partial representations of members at collection endpoints, i.e. `/events` returned only some info for each event, whereas `/events/:id` returned everything. now both endpoints return the same data.)
* relationships are returned as urls, e.g. `/stories/1` returns something like: `{ ... events: [{'url': '/events/1'}, {'url': 'events/2'}] ... }`
* every resource has a first-class endpoint (e.g. `/events`, `/stories`, `/articles`, etc)
* the only nested resource is `/stories/:id/watchers` which supports POST and DELETE methods for watching/unwatching a story.