Implement embedded-hal

[dbrgn]

In the meantime a lot of things have been happening in the Rust embedded space (see http://blog.japaric.io/).

The way to go for Rust on the Particle boards would probably be to implement the embedded-hal traits for the boards.

Introductory blogpost: http://blog.japaric.io/brave-new-io/

[jhlink]

This is incredibly exciting. Once I get a bunch of work finished by March's end, I plan on contributing to this in full force.

No experience in Rust yet, but I'm an embedded systems developer, and I can't wait to move to Rust from C/C++!!