Make and() and or() lazy

[justinbmeyer]

similar to && and ||, I think and() and or() should be lazy. For example, the following should pass:

QUnit.test("and is lazy", function(){
	var view = stache("<div>{{#and(this.isFalse, this.shouldNotBeRead)}}TRUE{{else}}FALSE{{/and}}</div>");

	var fragment = view({
		isFalse: false,
		shouldNotBeRead: new Observation(function avoidReadingThis(){
			QUnit.ok(false, "should not be read");
		})
	});

	QUnit.equal(fragment.firstChild.innerHTML,"FALSE", "evaled to false");
});

Currently this doesn't because Lookup() always Observation.temporarilyBind(data) so initialData can be peaked at ....

Lookup::value also warns about missing values. This would somehow have to be done later. Perhaps via some ScopeKeyData configuration ...

I think we'd want ScopeKeyData.initialValue to "temporary bind" if it's not already bound. This way, things that were already reading initialValue would still work.