Added tests for switching models in views, reported in issue #74

This commit add three new tests (let me know if I've put them in the correct place)
- A basic sanity test to see if switching a model in a model view is reflected in the properties
- A test that bind a view to a `<select>` and checks to see if its value updates when the view_model's model is switched
- A test identical to the one above except that it uses an `<input>`

Tests 1 and 3 pass for me, thus there is an issue binding to selects.