CHEF-4239: Quote git repository attribute to handle spaces
CHEF-4239: Handle specs run from dir with space
URI really doesn't know what to do with windows paths

Since we're here anyway...
Use quotes instead of shellwords so that escaping is done correctly on windows.

Conflicts:

	lib/chef/provider/git.rb
	spec/unit/provider/git_spec.rb
Apparently git.exe on windows only works with double quotes.

Conflicts:

	lib/chef/provider/git.rb
	spec/unit/provider/git_spec.rb