Change default port for web since it requires websockets (different protocol)
Change default port for web since it requires websockets (different protocol)

This also eases proxying from websockets to the native server, for
example with https://github.com/novnc/websockify:

./websockify.py 4081 localhost:4080

satoshinm/NetCraft,satoshinm/NetCraft,satoshinm/NetCraft,satoshinm/NetCraft,satoshinm/NetCraft