refactor negotiateContract for use with Renew
refactor negotiateContract for use with Renew

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