Reintroduce Tags

[bengreeley]

Add tags and metadata back in “so we can point to a bunch of great government sites, or authors, or startups, etc. that way, when a new one comes in, we can say look at all these other awesome XYZ sites that are already using WP.”

[jasmussen]

This seems like a good spot to add metadata:

[ryelle]

The tag, category, and flavors will be added as part of #132, closing in favor of that issue.