Use Composer for Mustache, Smarty and Twig.

Remove vendor Mustache.php library. Remove autoload configuration for
Mustache, Smarty and Twig. Update recommendation in README.

Signed-off-by: Justin Hileman <justin@justinhileman.info>
Update View_Mustache for v2.x

Yay!

Signed-off-by: Justin Hileman <justin@justinhileman.info>