Setting the "LowPower" mode on the main DownloadManager class will
cause it to halt all network activity and jobs will die.
You can revive it by changing it to NormalPower and optionally calling
the start() method to restart all jobs.
We reuse the NetworkManager lower level code in order to connect
to the Bitcoin P2P network.
This implements the basics for anyone wanting to be a player on
this network.