Don't add '-g' to defaults read command for NSGlobalDomain

Reading defaults of `NSGlobalDomain` fails. The provider would add a `-g` option when reading `NSGlobalDomain` defaults, which causes the command to fail and causes the provider to always set the value even if it hasn't changed.
This is what the provider does:
````
defaults read NSGlobalDomain -g NSAllowContinuousSpellChecking
=> The domain/default pair of (kCFPreferencesAnyApplication, -g) does not exist
````
Using both `NSGlobalDomain` and `-g` doesn't work (anymore?)
The following commands both correctly return the current value:
````
defaults read NSGlobalDomain NSAllowContinuousSpellChecking
defaults read -g NSAllowContinuousSpellChecking
````

Here is the issue I've created in the chef ticketing system. It this required for me to do, or can I just create pull requests to this repository?
https://tickets.opscode.com/browse/COOK-3585