Biography: Improve bra/cup size handling

Limit the bra/cup size to possible values (so no free entry field). Then more things can be done based on this field, like listings by breast size or showing models with similar cup sizes.
One problem is the variation from one cup size to another: what if the model gets another cup size because of weight gain/loss or plastic surgery? Do we use the new value that might correspond with her current figure but not with older photos?