Rule: Expected break inside case (Closes #258)

Closes #258 It will handle both `break` as well as `return` statements. However, it's not as smart as I would like it to be. It only checks top level nodes of `case` statement and doesn't try to verify that each code path uses return or break (I checked, JSHint does the same thing, but they don't check for returns). Also, I can't get error message to match JSHint, since they check the next node, and we can't do that. Ideally it should check if this is the last case/default statement inside switch and not warn about lack of break there.