update arm mass according to documentation on youbot-store.com
Update base.gazebo.xacro

Update wheel contact spring values 

See mas-group/mas_industrial_robotics#5 for discussion.
These values were chosen after lots of trial and error and then finding this discussion: 
https://bitbucket.org/osrf/gazebo/issue/680/feet-drift-when-standing-due-commit

Any kp over 150000 works.

This Closes mas-group/mas_industrial_robotics#5
Merge pull request #1 from moriarty/patch-1

Update base.gazebo.xacro
Merge branch 'hydro-devel' of https://github.com/mas-group/youbot_description into hydro-devel
update  interias of the arm
correct formatting
update ASUS Xtion gazebo file for hydro
rename camera tower
add urdf for youbot with arm and RGB-D cam
get rid of color warnings in simulation
correct simulated sensor parameters for the ASUS Xtion
add depth_registered topics to the simulated ASUS Xtion
increase efforts
comment safety_controller in order to make trajectories work in simulation
correct indentation
add parentheses