Merge pull request #10 from pavansoundara/battery-data

We've released a binary version of the drivers which publishes the this version Note: will investigate switching both internal and external code to use: http://docs.ros.org/api/sensor_msgs/html/msg/BatteryState.html in the future.

Adds:

• total_capacity
• current_capacity
• battery_voltage
• supply_voltage
• charger_voltage

Removes:

• errors

Contributors: Alex Moriarty, Pavan Soundara