Nested model failure test

I've found a bug. When you set ng-model to some nested value (eg. ng-model="foo.bar.items") dragdrop stops working.
I'm submiting a test.
The problem is how model value beeing evaluated (scope[dropModel]) (angular-dragdrop.js line 60 and so on). I think this should be scope.$eval(dropModel), or something like that.

--EDIT--
I think i've fixed it. Check out 2fa5439 commit.