respect hub.lease_seconds (fix #46)

timeline reload in UI, other small fixes

and atom feed generation to some extent, as well as the way mentions are
stored

when registering incoming status mentions, add Travis CI file

local followers. Remote users' usernames SHOULD be case-sensitive

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.

fetch webfinger information of mentioned accounts