fix bug 937723 - correctly handle the difference between document tags and search filter tags.

This also fixes an inconsistency in indexing the tags, they are now enforced case sensitive.
The “Web Developement” search filter had also a broken tag (with quotes).
Merge pull request #1662 from jezdez/case-sensitivity-tags-937723

fix bug 937723 - correctly handle the difference between document tags and search filter tags.