bump version to 0.3.20
bump version to 0.3.20

ros/catkin,shyamalschandra/catkin,beni55/catkin,scpeters/catkin,beni55/catkin,thaddeustaylor/catkin,meyerj/catkin,thaddeustaylor/catkin,thaddeustaylor/catkin,harmishhk/catkin,jack-oquin/catkin,asmodehn/catkin,jack-oquin/catkin,ros/catkin,scpeters/catkin,wkentaro/catkin,harmishhk/catkin,shyamalschandra/catkin,wkentaro/catkin,meyerj/catkin,wkentaro/catkin,ros/catkin,jack-oquin/catkin,meyerj/catkin,harmishhk/catkin,scpeters/catkin,asmodehn/catkin,shyamalschandra/catkin,beni55/catkin,asmodehn/catkin