AMCL parameterization.
New maps
Simplified collision model
deleted uncommented comment in guardian.gazebo
Skid steer plugin adapted to command correct velocities

Bug #1897
uses adapted skid steer drive and not husky plugin
corrected guardian_robot_control.yaml configurations for odometry
calculations
Skid steer plugin publishes odom 

Comented guardian_robot_control, now odom (msg and TF) is published by
skid steer plugin

Deleted no longer used husky related files