initd: not starting due to incapability to load iptables modules

[daenney]

Some people still maintain their own kernels (especially Xen-providers are known to do this) and it might so happen that the modules vuurmuur tries to load cannot be loaded because they are baked right into the kernel.

When starting we should first check whether the modules are already loaded or the functionality is already provided by the kernel, if not then try and load the actual modules.

The current workaround is to uncomment the line VUURMUUR_MODULES in /etc/default/vuurmuur so that vuurmuur can actually start on hosts that have an alternate kernel.