Don't install the tomcat manager apps package if we're not going to use it

While the deploy_manager_apps flag attribute exists to allow users to opt out of deploying the manager and host-manager webapps, the recipe still installs the tomcatX-admin or tomcatX-admin-webapps package even if that flag is not set. This patch causes the recipe to install the extra package only if deploy_manager_apps is set.

See http://tickets.opscode.com/browse/COOK-3370