Emscripten port

- Add new configuration `emscripten` to compile BLIS into [Asm.js](http://asmjs.org) with [Emscripten](https://en.wikipedia.org/wiki/Emscripten). Emscripten tools (`emcc`, `emar`, `emranlib`, ...) must be in the `PATH` to build the configuration.
- The `Makefile` is modified to reflect the changes in the build process. Most importantly, the test suite config files (`input.general` and `input.operations`) are embedded into the test suite binary, and thus the binary is rebuilt whenever they are modified.