Building examples for all nRF52 variants out of the box

[TorstenRobitzki]

It should be able to build nrf52 examples out of the box for:

• different variants of the microcontroller like nrf52832, nrf52840 or nrf52820
• provide abstractions for used peripherals like flash, GPIO or temperature sensors.
• Especially GPIO pin assignment should be easily changeable to have the examples run on different nordic eval boards, other breakout boards or on custom hardware