Gets information about a key ring.
The 'callback' parameter specifies a function which will be called when the operation completes (or an error is encountered). If the 'callback' parameter is not specified, then the method will block and will not return until the operation completes (or an error is encountered).
The callback for this method is defined as:
'err' is the error that occurred. If there was no error, then 'err' is 'null'.
'err' has 2 properties which hold detailed information:
This method gets information about the currently-selected KeyRing.
When the information is returned, the class clears the KeyRing* properties and repopulates them with a single item that contains the key ring's information. The KeyRingList event is also fired.