added uniform sampling to ex4
added uniform sampling to ex4

giorgiobornia/femus,saikanth88/femus,saikanth88/femus,FeMTTU/femus,FeMTTU/femus,saikanth88/femus,giorgiobornia/femus,eaulisa/MyFEMuS,saikanth88/femus,FeMTTU/femus,giorgiobornia/femus,eaulisa/MyFEMuS,FeMTTU/femus,eaulisa/MyFEMuS,giorgiobornia/femus