timeline reload in UI, other small fixes

adding attachments display to static views

Mostly resolves #8, though attachments are still not displayed in public view

Adding better errors for the API controllers, posting a simple status works from the frontend now

behaviour with Turbolinks enabled, optimizing Rabl for production

simplify FanOutOnWriteService, add /api/accounts/lookup method

POST /api/statuses                  Params: status (text contents), in_reply_to_id (optional)
GET  /api/statuses/:id
POST /api/statuses/:id/reblog

GET  /api/accounts/:id
GET  /api/accounts/:id/following
GET  /api/accounts/:id/followers
POST /api/accounts/:id/follow
POST /api/accounts/:id/unfollow

POST /api/follows                  Params: uri (e.g. user@domain)

OAuth authentication is currently disabled, but the API can be used with HTTP Auth.