Guilhermito/pcf8591 driver style

Convert the ADC driver to a driver sub drivers system.
This allows the usage of external ADC devices.
One new function of the ADC driver combines all available ADC channels.
Included a new PCF8591 I2C ADC subdriver.
Modified the battery module to use the new driver system.

Only the CC target was modified and it will probably brake all other targets, therefore this is to be considered as WIP and the purpose is to receive feedback before re-factoring the other targets.