ENG-83: documented type support for search attributes.

git-svn-id: http://svn.terracotta.org/svn/ehcache@7777 b9324663-ca0f-0410-8574-be9b3887307d
Merged 7777


git-svn-id: http://svn.terracotta.org/svn/ehcache@7778 b9324663-ca0f-0410-8574-be9b3887307d