Adds private flag for 1-1 messages.
Adds mention flag if contains user's nick.
Use tags to determine if message is highlighted.
Refactor message construction out of pusher.
Apparently :user is for @ and :highlight is for no-@.
Use some instead.
Remove highlight check; Flowdock no longer sends it.
Add message handlers.
Merge pull request #7 from tomitm/types

Support for private/mentioned flag