Inability to sync without connection to original validator

[orogvany]

in semuxBft,

 // Pick 2/3th active validator's height as sync target. The sync will not be
            // started if there are less than 2 active validators.
            OptionalLong target = activeValidators.stream()
                    .mapToLong(c -> c.getRemotePeer().getLatestBlockNumber() + 1)
                    .sorted()
                    .limit((int) Math.floor(activeValidators.size() * 2.0 / 3.0))
                    .max();

            if (target.isPresent() && target.getAsLong() > height) {
                sync(target.getAsLong());
            }

if a user is syncing from scratch and cannot connect directly to one of the main original seed nodes, they cannot sync. We should not need to get the height from one of main validators if we are not ourselves a validator.

[orogvany]

fixed in #130