This commit alters the NodeAlias String method to trim null-bytes from
the end of the alias. This is helpful for presentation in contexts such
as the GetInfo response.
This commit adds a check to `updateChannelFee` which skipssending the
`update_fee` message when the channel is not eligable for forwarding
messages (likely due to the channel's `RemoteNextRevocation` not yet
being set).
This addresses #470.
Benjamin Congdon