Use chef-runner on Windows (part 1)

[mlafeldt]

Allow to use chef-runner under Windows.

• [x] Fix tests to run under mingw32 ("Git Bash")
• [x] Fix tests to run under cmd.exe
• [x] Cross-compile Windows binaries
• [x] Disable color output (done in #27)

TODO:

• rsync: use destination-default permissions (--no-p --no-g --chmod=ugo=rwX) (can be done with #28)
• Write docs