consensus set tested for ErrInvalidConsensusChangeID
consensus set tested for ErrInvalidConsensusChangeID

The consensus set is expected to return
modules.ErrInvalidConsensusChangeID if an invalid consensus change id is
provided. There is now a test to verify that behavior.

ericflo/Sia,rivine/rivine,NebulousLabs/Sia,rivine/rivine,mtlynch/Sia,MrStrong/Sia,ChrisSchinnerl/Sia,mnsl/Sia,MrStrong/Sia,mnsl/Sia,ericflo/Sia,mharkus/Sia,ChrisSchinnerl/Sia,mtlynch/Sia,Mingling94/Sia,mharkus/Sia,NebulousLabs/Sia,johnathanhowell/Sia