Events Feed Poller behavior

This branch adds a higher lever abstraction (`EventsFeedPoller` class) which continuously polls the events feed and looks for new entries. Once a new entry is found an appropriate event is emitted.

Keep in mind that the events emitted by the client are more granular then one returned in the events feed. For example, in the events feed we return `services.timeout` event, but the `EventsFeedPoller` class emits a separate `service.timeout` event for every service.

Note: Tests are W.I.P. and will be available shortly in the farscape repository.