Allow specifying the "ensure" parameter in all calls to"package"

This allows installing a specific version of PHP by passing a version string for "ensure", e.g. ensure => "5.3.3"

This is backwards-compatible, with the possible exception of the change to the php::fpm::daemon class: the $ensure parameter will now be passed straight to "package" instead of using one of "installed" or "absent". The default value for $ensure in php::fpm::daemon is "present", which I'm pretty sure is the same as "installed" for all the package providers.