This includes:
* Cmake clean up - thanks @Qyriad
* Windows binaries saved after each appveyor build
* A bump to the Visual Studio version that we use to build it
* An appveyor cygwin script for building firmware, it doesn't work but it seems like someone might pick it up and make it work, or blow it away if we switch to Travis firmware artefacts
By default, CMake assumes that the project is using both C and C++. By
explicitly passing 'C' as argument of the project() macro, we tell CMake
that only C is used, which prevents CMake from erroring out if a C++
compiler doesn't exist.
