Ember "release" version now requires Handlebars 2.0.0
Test against Ember 1.7.1, Handlebars 1.3.0

Now that more recent Ember versions are moving to HTMLBars and
Handlebars 2.0, we need to add a test to ensure we maintain
backwards compatibility.
Escape interpolations by default

This is in order to get the expected handlebars-like mustache
escaping behavior. Unescaped interpolation made possible via the
common tripple curlies mustache.