Log Message:
Update ruby-ferret to version 0.11.6.  Changes from version 0.11.4
include:

+ Install as a Ruby gem.

* Fixed major bug in term vectors which was in turn affecting
  highlighting
* Fixed memory leak in PerFieldAnalyzer
* Fixed range query highlighter
* Fixed memory alignment issues on Solaris
* Added :use_keywords option to query parser so you can now turn
  of keywords so a search for OR will work
* multiple other bug fixes