guard_interpreter default change for powershell_script, batch resources

This change modifies the default for the `guard_interpreter` attribute for the `batch` and `powershell_script` resources so that for each of these it uses those resources to execute guard expressions by default. That is to say, for `powershell_script`, the `guard_interpreter_attribute` will be set to `:powershell_script` and for the `batch` resource it will be set to `:batch`. 

It matters unfortunately because powershell will use utf16 by default, and when reading the data back in via ruby, it treats it as binary and comparisons against text in the specs fails. It was fun discovering that.