filter suggested properties in case config

to only include properties not already selected

![screen shot 2014-07-03 at 11 26 08 am](https://cloud.githubusercontent.com/assets/137212/3471861/681f31de-02c6-11e4-8c75-5c3c362d0072.png)

(note how 'VitA_1_previous' no longer shows up as a suggestion)