Added queue for notifications to prevent pebble from crashing fixes #20

[smurfy]

I added a queue system which only sends one notification every 250ms to the pebble.
I tested with 256 messages in the queue and pebble does not crash. (crashes if you don't delay)

Queuing is in a thread so it does not interfere with other pebble communication.

[smokku]

Shouldn't this be implemented in WatchConnector?

[smurfy]

I thought about it, but then decided to implemented it not in the connector because the queue is a high level fuction, while the communication itself is lowlevel.

But if you like i can move the code over.

[smokku]

With current implementation it is still possible to flood Pebble with messages. Only notifications source of messages is protected - others are not. i.e. I could flood Pebble with MUSIC messages.

[smurfy]

Ok, makes sense, i will update my PR over the next couple of days.

[bsx]

Perhaps it would also make sense to have a maximum queue length and drop messages after that, otherwise you might add several thousand messages to the queue and keep the Pebble busy for a while. The queue length could maybe even be configurable through the UI.

[smurfy]

@bsx yea makes sense. whats the best approach, dropping new messages or old ones?