Optimize Sense has to be min #22
Description
Currently, PlasmoBenders expects all subproblems to be minimization problems. I think we should go through all subproblems and either convert them to minimization problems or else throw an error if they are not all minimization. This is important for the M attribute that is set in the optimizer since, if you are doing a minimization that can have a negative value, M needs to be negative as well.