Removal of section 5.2.2: Search Filters.

I've been planning for a while to remove Section 5.2.2 from the Contacts API
specification: http://dev.w3.org/2009/dap/contacts/#search-filters

I imagine that a number of people have thoughts on this removal. If
implementors still wish to experiment with this feature then I would
consider adding it back in but for now its complexity far outweighs its
benefits considering that it adds little value to the overall functioning of
the API.

If any implementors have significant concerns please let us know.

- Rich