Add method to retrieve all the items of a list

[varvar]

HI, I've added a method which can retrieve all the items of a list. For example : all failed queues

[danhunsaker]

I'd do a couple of things to this before expecting a merge. First, most of the Resque methods have more descriptive names than the underlying Redis command, so I'd change the method name to something else that reflects its purpose rather than its internals. Second, I'd make the second two arguments optional, and default them to retrieve the full list. This will increase the added value of such a function.

[danhunsaker]

Other than that, though (and the coding style - spaces between function arguments, please), it looks good here!