cleaning up tags

1. When tags are displayed, they should have the same format as used by the tags display, i.e. replace '=' with ': '.

2. Tags are of no value to guests. Don't display them.

3. Inherited tags are of no value to basic users. Don't display them.

These changes will be included in the next release. And yes, I'm starting to think about the expert interface which gives users the ability to add/change/remove tags as well as search on tags and add tagged topics to a namespace.