Fixes for RSpec and Cucumber tests on Windows

* Do not load Berkshelf::API
* Add api_client and not_supported_on_windows tags to RSpec tests
* Add api_server tag to Cucumber features requiring Berkshelf::API
* Skip these tags on Windows
* Use && instead of ; in command line operations
* Rewrite checks using temporary directories
* Use double quotes when shelling out
* Remove stderr redirects to /dev/null
* Git on Windows does not create full path to tmpdir, do this in clone
* Ensure that there is a / in Mercurial URIs
* Work around Thor::Shell::Basic behaviour differences on Windows
* Disable Yard runs on Windows