fixes for ruby 2.1.3

fixes for windows, plus fixes for solaris
Merge pull request #304 from opscode/lcg/ruby-2.1.3-windows

Lcg/ruby 2.1.3 windows
Ensure `tar` is available for native extension compilation

Many gems ship with native extensions that assume tar will be available
in the PATH during the build process. Although we would hope these native 
extensions respect environment variables like `TAR` or `PROG_TAR` it’s 
not always the case. :-(