Improve use of 'tags'

[CallumWalley]

Currently tags on the supported apps page are pulled from a file in an external repository.

This could be replaced with a 'domain whitelist' file somewhere in this repo, then any matching tags in an article meta are used in the supported apps page.

[CallumWalley]

#117 Adds page tags to supported app badges (in addition to the regular ones).

Currently any badges without CSS rules are hidden, so spammy tags are hidden.

Improvements to be made.

• de-duplicate 'machine' tags. e.g. 'mahuika'. Also, decide if this is a tag we want app pages to have.
• Remove spam tags (might be good to have an 'approved tags' list).
• Filter out unshown tags.
• Propigate tags other way? E.g from module_list.json

[CallumWalley]

Done-ish.

See 'improvements to be made'