Kernel minimization (#334)

* adds patch to remove unused kernel components

* new boards, rebase patches to match

* rename boards for deployment

boards/nordic/nrf52840_dongle_opensk/README.md

@@ -0,0 +1,41 @@
+Platform-Specific Instructions: nRF52840-Dongle
+===================================
+
+This is an adapted nrf52840\_dongle made to work with OpenSK.
+
+The [nRF52840 Dongle](https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-Dongle)
+is a platform based around the nRF52840, an SoC with an ARM Cortex-M4 and a BLE radio.
+The kit is uses a USB key form factor and includes 1 button, 1 red LED and 1 RGB LED.
+
+## Getting Started
+
+To program the nRF52840 Dongle with Tock, you will need a JLink JTAG device and the
+appropriate cables. An example setup is:
+
+- [JLink JTAG Device](https://www.digikey.com/product-detail/en/segger-microcontroller-systems/8.08.90-J-LINK-EDU/899-1008-ND/2263130)
+- [ARM to TagConnect Adapter](https://www.digikey.com/product-detail/en/tag-connect-llc/TC2050-ARM2010/TC2050-ARM2010-ND/3528170)
+- [10pin TagConnect Cable](https://www.digikey.com/product-detail/en/tag-connect-llc/TC2050-IDC-NL/TC2050-IDC-NL-ND/2605367)
+
+Then, follow the [Tock Getting Started guide](../../../doc/Getting_Started.md)
+
+JTAG is the preferred method to program. The development kit has the JTAG pins exposed either
+through the half-moons pads or, below the PCB, on a Tag-Connect TC2050 connector footprint.
+You need to [install JTAG software](../../../doc/Getting_Started.md#optional-requirements).
+
+## Programming the kernel
+Once you have all software installed, you should be able to simply run
+make flash in this directory to install a fresh kernel.
+
+## Programming user-level applications
+You can program an application via JTAG using `tockloader`:
+
+```shell
+$ cd libtock-c/examples/<app>
+$ make
+$ tockloader install --jlink --board nrf52dk
+```
+
+## Debugging
+
+See the [nrf52dk README](../nrf52dk/README.md) for information about debugging
+the nRF52840 Dongle.