View registry memory leak

I think `setElement(null)` or should be called as part of `remove()` to ensure the view is removed from the view registry.

**Install Dependencies**
`npm install && bower install`

**Test**
`grunt test`

**Build**
`grunt build`

- [ ] @doug-martin 
- [ ] @andymoon
- [ ] @jgchristopher
- [ ] @jkc
- [ ] @jvanwinkle