Fix for missing stack name in opsworks.php template on deploy

Noticed that the stack name was not being passed into the opsworks.php.erb
template, as it is in configure.rb. Just copied over the code from the
configure.rb recipe.
Merge remote-tracking branch 'upstream/master' into fix-stack-name-php-deploy
Merge branch 'fix-stack-name-php-deploy' of git://github.com/danapplegate/opsworks-cookbooks