GitLab

Added a menu item to set the low freqency crystal. 

this adds and option to set the LFCLK on the nRF52DK which can also be used on custom boards with or without an external 32.xxxkhz crystal, defaults to use external crystal

Add platform.txt recipe for 'Export compiled binary' as a hex file

Add new board variant for Waveshare BLE400 http://www.waveshare.com/product/modules/wireless/bluetooth/nrf51822-eval-kit.htm

Add RedBearLab nRF51822 link

Add RedBearLab BLE Nano link

from
https://github.com/ARMmbed/nrf51-sdk/blob/master/source/nordic_sdk/compo
nents/drivers_nrf/delay/nrf_delay.h

Minor update to #12.

Tweaks to #12

Update README.md for first use case

was downloading version 2.0.1 of the soft device but the board definition had 2.0.0 which resolves issue #13

link was to the preview release not the current dk, both link to the same file for now

an extra step for the first out of box experience required for nrf52, took me a few hours to test why the following did not work:
```
void setup() {
  pinMode(PIN_LED1, OUTPUT);
  pinMode(PIN_LED2, OUTPUT);
  pinMode(PIN_LED3, OUTPUT);
  pinMode(PIN_LED4, OUTPUT);
}

void loop() {
  digitalWrite(PIN_LED1, HIGH);
  delay(50);
  digitalWrite(PIN_LED2, HIGH);
  delay(50);
  digitalWrite(PIN_LED3, HIGH);
  delay(50);
  digitalWrite(PIN_LED4, HIGH);
  delay(50);
  digitalWrite(PIN_LED1, LOW);
  delay(50);
  digitalWrite(PIN_LED2, LOW);
  delay(50);
  digitalWrite(PIN_LED3, LOW);
  delay(50);
  digitalWrite(PIN_LED4, LOW);
  delay(50);
}
```

Add tools credits

Add flashing a SoftDevice section