Revamp deploy.py

Now the script supports more flashing methods:
- JLink (with tockloader)
- OpenOCD (with tockloader)
- pyOCD
- Nordic DFU
- none (will produce an IntelHex file)

Also merged the contributions from:
- Yihui Xiong to support the Makerdiary USB dongle board
- Dennis Geurts to support Nordic DFU

Doc updated accordingly.

Imported 2 patches for Tock kernel:
- 06-add-set_vector_table_offset.patch (upstream tock/tock#1579)
- 07-nrf52-bootloader.patch (upstream tock/tock#1681)

boards/nrf52840_mdk_dfu/layout.ld

@@ -0,0 +1,10 @@
+MEMORY
+{
+  rom (rx)  : ORIGIN = 0x00001000, LENGTH = 188K
+  prog (rx) : ORIGIN = 0x00030000, LENGTH = 832K
+  ram (rwx) : ORIGIN = 0x20000000, LENGTH = 256K
+}
+
+MPU_MIN_ALIGN = 8K;
+
+INCLUDE ../../third_party/tock/boards/kernel_layout.ld