Issue #126: Reduce redundancy in mvc/View by combining `View#render`,
`View#renderPageView`, and `View#redraw` into `View#render`.

- Changed `View#render` to provide the functionality of `View#render`,
  `View#renderPageView`, and `View#redraw`--that is, any situation where View
  should change the contents of `this.el` on the user's behalf using the
  template given in `View#generateHtml`
- To accomodate mvc/ViewManager, removed the `this.shell` wrapper (was added by
  `View#renderPageView`) and changed the constructor to guarantee `this.el`'s
  existence. `this.el` is now the only framework-imposed DOM node for Views in
  *every* situation.