Fixing Roomba config file & laptop battery monitor fix

Some recent changes in the main Turtlebot repository were not reflected in the roomba launch config. e8e268c fixes that.

Besides that I have also added some code to the laptop_battery.py (commit 7c7e2f5 ) so that the new power management scheme (the one, where all the power information is available in `/sys/class/power_supply` instead of `/proc`) is supported. I hope that it can be merged in the main repository.