Improve handling of EULA-protected builds — discussion

At the moment, protection is based on path containing either 'origen' or 'snowball' in the name. We should improve that to allow per-build protection in an easy way.

At the moment, our implementation is limited by what mod_rewrite can support (i.e. it has support for path processing and can potentially check for existence of files and environment variables, and not much else). Discuss if we can solve it with mod_rewrite or if more complicated approaches are needed.