Update Controller Hardware to Version 4.0

## Update controller board to rev 4.0.

- New version contains BTLE via Microchip RN4020 module
- Voltage supervisor with hard reset capability from bluetooth
or via microcontroller
- Current monitor for solar and external charging current
- Move 2.8V linear regulator and add RF filtering caps to fix RF
interference problems on GSM transmission.

## Rename combined_controller to controller

We don't have different assembly variants anymore so the
combined isn't needed.

## Fix pcb build system to properly find eagle in PATH