Titan.isConnected() checks in Worker (also in Titan.Client of course)

[soygul]

• [x] Send pending messages when connected.
• [x] Test that messages delivered on invisible threads don't mess up chat message loading (Profile.upsertMessages will probably mess things up as it upserts even when the chat messages was not loaded)
• [x] Queue messages when not connected rather than silently throwing exception. (Edit: this is already done automatically while persisting messages to DB with state=NEW).
• [x] Reconnect automatically while service is running (but give up after x-many retries or no Android internet conn available).