Windows color support - experimental

The idea is to pipe the `elixir` output to another app (`bin\wac.exe` by ) that intercepts ANSI sequences and converts them into colors. If the `wac` app is not found, we simply use the default output...

### There is still a problem with exclamation marks that disapear, so do not merge this branch just yet !!!


![image](https://f.cloud.github.com/assets/155977/863894/b8b2fd3e-f614-11e2-8ef0-5e2df196090f.png)

To test it, run `make compile_windows`, and make sure you have GCC installed.