Add 'insane_notify' options

This pull-request is a proposal.
Enable 'insame_notify' option will be faster sending.

It became 150 minutes to 8 minutes in my environment.
> @75,000 APNs devices, 1 connection, ec2 micro, no_check_for_error

To save the 'delivered' flag each sending, causes the IO wait of DB.
The 'insame_notify' change to mark delivered before taking to handles.

Note:
* If application crashed, it will not be sent up to 5,000 (batch_size) notifications
* `delivered_at` is always not set