Added Flowdock protocol adapter for the bot. Refactored campfire bot into a base streaming protocol adapter for common functionality.

Summary: First pass. Flowdock supports interesting message types (like replies to messages), but for now implementing a standard messaging interface.

Test Plan: Ran both a Flowdock bot and a Campfire bot. Made sure both still connected and responded properly to the Object Handler.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4983