Append 'ws://' prefix if url starts with localhost

[patrickReiis]

Related: fiatjaf/nak#22

Without thinking much and doing things in a hurry, the commit above is wrong because nak req or nak event actually use under the hood the function NormalizeURL, and I thought they used the file relay.go in the nak repository.

However, the commit above is not totally wrong, in a sense that the commit doesn't need to be removed, because it works with the relay flag. Image above.

My bad.