Modify friction parameters fix slip while driving

It has come up a couple times that driving the husky base on the ground plane created in gazebo empty_world isn't very realistic. I can't find any reference for the units on these parameters, but mu1 represents static friction in the fdir1 direction, and mu2 represents static friction in the direction perpendicular to fdir2 in the XY plane, ie forward friction and sideways friction. I quickly tested a bunch of values, and these numbers seem fairly realistic.