WIP: rebase 5

[anxiousmodernman]

@wez I've resolved the merge conflicts between our branches. Can you take a look at this one to see if it builds for you on Mac?

I am able to build this in the docker container (we'll need to edit the Dockerfile before merge, as it points to this branch). My native build was recently messed up after installing some android toolchains on Arch. I'm going to trust the Docker build in the meantime.

[anxiousmodernman]

Update: the blinky example was building fine natively. ble_app_template yields some missing references:

Which is odd, because all the symbols end up in bindings.rs, from what i can tell, so adding shims and nRF5-sdk recursively puts them there.

[anxiousmodernman]

Okay, got ble_app_template to compile. I was missing the NRF_LOG feature in my Cargo.toml, so while the required functions ended up in bindings.rs, my app_config.h was generated as empty, and I got an error from the linker.

According to the docs, features are the way to allow conditional compilation, which is what we want to enable here. Yet, we have to check in Cargo.toml, so a question here is what features to enable by default?

[anxiousmodernman]

Closing in favor of a squashed-down #9