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_dongle_dfu/build.rs

@@ -0,0 +1,4 @@
+fn main() {
+    println!("cargo:rerun-if-changed=layout.ld");
+    println!("cargo:rerun-if-changed=../../third_party/tock/boards/kernel_layout.ld");
+}