Making models more robust
 - Models now have a .reset() function. This sets the model back to default values + the vals passed in
 - Model.set now can take {reset: true} as an options, resetting the model with the new values
 - Model.toggle will toggle a boolean value
 - Computed properties now use their cache instead of re-evaluating on every get()
 - Tests now pass with the last HTMLBars update