Do not provide completions for contacts which have already been selected.
Merge remote-tracking branch 'upstream/master' to get resizing fixes.
Added a BOOL property to control the filtering of already-chosen contacts,
changed to perform the filtering within the Predicate being used, and added
documentation of the new property.
Merge pull request #34 from brunchboy/master

Do not provide completions for contacts which have already been selected...