use Kostache from Composer, fix for latest Kostache

Using Kostache from Composer is a lot more intuitive than having to
manually install the Mustache.php dependency myself when I clone
the template.

The latest version of Kostache appears to have broken some
backwards compatibility with this project template. I added a
"temporary fix" to the Controller_Base to fix it for now - not sure
if this is the right way to do it.

Credit to Lorenzo Pisani (@Zeelot) for a little code from his
template that I copied and pasted into the Controller_Base class.