Make Consensus Work

[charles-e]

Problem

There two problems
First:
in bank.rs
self.epoch_authorized_voter(&voter)
was not working the way I thought it did. (you need to pass it a voter account - I was passing an authorized voter. As as result we fell back to rando voter all the time

Second:
In vote_group_gen,rs I was putting the wrong keys into the lookup table - so even if we had gotten past the first problem we would still not be able to vote - and we were lucky that we did not get here - because noone with stake would have been voting

Summary of Changes

Fixes #

1 vote_group_gen now has a method: can_group(pubkey) -> bool
This returns true if the pubkey is in the staked voter list used for building groups.

2 bank.rs now calls can_group(voter) instead of self.epoch_authorized_voter(&voter) to decide whether or not to use rando_voter.

3 in vote_group_gen.rs VoterGroupGenerator::new is modified to build the map for lookup to support can_group(). It also now puts the correct pubkeys into the array we use for building groups.