Jdmundrawala/windows env path

Fixes issues: 
https://github.com/opscode/chef/issues/2016 
https://github.com/opscode/chef/issues/2009

Includes changes from/Should replace:
https://github.com/opscode/chef/pull/1876
This uses the windows api instead of find/replace and I've added functional tests
ok, :tableflip:, 32k it is, and we'll figure out if we need to care about the max length as customers hit issues...