Refactor AEPsych models to not require dim instead of lb, ub in constructor

AEPsych models currently require lower bounds and upper bounds of parameters to be passed into their constructors, but the model itself should not have to worry about the bounds of the space; that's the responsibility of the strategy. All the model really needs to know is the dimensionality of the space. Removing the lb and ub from the constructor would reduce a lot of boilerplate. Wherever a model method requires self.lb or self.ub, we should be able to refactor it so that the method takes those as parameters that can be passed in by the strategy.