WebTag: initial release

* Supports private tags for logged-on users (a) attaching and detaching
  tags to records, (b) tag management in `/yourtags`.

* Adds tag list and tag-editor to brief record view for logged users.

* NOTE: Disable caching of 'HB' templates to see tags in search results.

Signed-off-by: Krzysztof Lis <krzysztof.lis@cern.ch>
Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>