Review and improve mechanism to provide 3rd-party features

Currently, we wrap (in a 1-1 mapping) most 3rd-party features as "requirements" into features of ours. It allows to show our license and lable when installing.

We should think about other approaches, and choose the best one:

• Get rid of our features and directly include 3rd-party features in site. Keep our features only when we want an assembly of several 3rd-party features (we do it for springide)
• Prefer inclusion over requirement so that we can restrict the version we allow for 3rd-party features. If someone wants a different one, he'll have to uninstall the JBDS "supported" feature first.