Fix to display community logo if set. In case the community has a parent, the parent logo will be displayed unless the subgroup has its own, the default one will be displayed if none of them have set a customized logo for the header.
Comparing the [ns_info version] against a.b.c is not possible. InsteadI use a combination of the version and the patchlevel to be sure thatwe are running on aolserver 4.5.1; in order to know if the nscache moduleshould be loaded or not.