Correcting the biomass objective function

The biomass objective function (BOF) of CarveMe does not add up to 1 mmol/gDW/h directly after the draft reconstruction. However, to get feasible results from a model this reaction should add up to 1 mmol/gDW/h. Thus, the module biomass was created to check if the BOF of a model is consistent and if necessary the BOF is adjusted to add up to 1 mmol/gDW/h.