lnwallet: reverse order of signatures when spending the funding output
lnwallet: reverse order of signatures when spending the funding output

This commit is a follow up to the prior commit, as since we reversed
the order of the pubkeys in the multi-sig scripts, then we also need to
reverse the order of the signatures that we use when attempting to
spend the funding output directly.

ddustin/lnd,aakselrod/lnd,ddustin/lnd,LightningNetwork/lnd,aakselrod/lnd,LightningNetwork/lnd