Update module::ini to allow specifying RPM pkgname directly

This changes the logic in module::ini so that calling classes can specify a package name directly without having to worry about what $phhp_package_name might be.  This gives the ability to use this module for e.g. php53u from IUS without having to manually override params.pp.

I understand this isn't ideal as it changes functionality slightly, but I think it's worth it to make it a bit more flexible.