Added variance method to beta distribution
Added variance method to beta distribution

akrawitz/jstat,smarden1/jstat,cmpolis/jstat,smarden1/jstat,akrawitz/jstat,jstat/jstat,NorthDecoder/jstat,ggonzale/jstat,jstat/jstat,NorthDecoder/jstat,JeebsM/jstat,ggonzale/jstat,JeebsM/jstat,jamescgibson/jstat