Create a /tags page for an ordered list of all workshop tags

[moosichu]

Basically, it would be good if we could have a page where all workshop tags created so far can be viewed. This probably means scraping tags from all the workshop metadata entries and storing them in the database as a cache.

Other info that we could also scrape could include the number of times each tag appears.

The reason for this is to make sure we don't create many variations of essentially the same tags, by making existing ones easily searchable. (So maybe this page should have a filter and fuzzy-search as well, for the fuzzy search we could also implement some regression testig. eg. If someone creates a workshop with the tag coding when a programming tag already exists, we can then make sure that in the future when someone searches coding, a the programming tag entry pops up. This would also then apply to searches for workshops when that is implemented at some point).

[moosichu]

See pull #163 for discussion on this!