Fix for tests on Windows

Currently RSpec and Cucumber tests are failing on Windows. Partially due to Berkshelf::API not running on Windows. The rest are mainly differences in paths and shell commands.

This pull request contains fixes to get all tests to pass. With the exception of one change in GitLocation this only touches the tests.

The change in clone was needed because Git on Windows by default does not create the leading directories in a destination path. I just copied the line from MercurialLocation to resolve this.

The added tags (api_client, api_server and not_supported_on_windows) are filtered in the Guardfile. I've disabled Yard runs because it tries to fork() which doesn't work on Windows.