Merge remote-tracking branch 'wberrier/master' into master

* wberrier/master:
  prevent an error when no search string is given
  Return partial results if the search takes a long time
  implement caching system for big/slow ldap servers
  make search fields configurable
  Add support for an optional display column
  Fix for python 2.6: add position indexes to format strings
  Add query filter section (in order to pare down results)
  Return results in a format that mutt expects
  fix typo in reference to .rc file
  Add Wade Berrier (me) to author/copyright list