Use Omnibus copy/delete on Windows instead of cp/rm

Using cp would presume we're running under MinGW, which is not currently
installed on the build slaves by https://github.com/opscode-cookbooks/omnibus
Merge pull request #264 from opscode/btm/libyaml-windows-cp

Use FileUtils.cp on Windows instead of cp
Create libyaml-windows directory at build time, not compile
Create openssl-windows directory at build time, not compile
Do not execute commands at compile time
Use windows_safe_path when shelling out on Windows
Clarify supported branches
General README and gemspec cleanup
Version omnibus-software with omnibus
Make Copyright header consistent
Cleanup appbundler
Cleanup autoconf
Cleanup automake
Cleanup berkshelf
Cleanup berkshelf2
Cleanup bundler
Cleanup bzip2
Cleanup cacerts
Cleanup chef-gem
Cleanup chef-vault