Fix big memory leak when relying on View#remove to cleanup

Since a single/global viewMethods was previously used to store event hashes, if you were done with a view and only relied on View#remove (since #3) for cleanup rather than calling unbindXEvents manually, then even if you disposed of all of your own view references, Backbone Declarative's viewMethods variable would hold a reference to each event method which, by closure, would contain the Views themselves.

We're still keeping a reference to all the bound events/methods, but by doing it on a per-view level the garbage collector can clean everything up if no external references are kept.

All tests still pass.