Tagging of videos (WIP)

(This is different to the video category system)

* This would simply be the ability for any user to tag any video with any tag repeatedly.
* Ideally you would want an increased cost for the initial creation of a tag
* Ideally you would want a way to charge a different fee depending on the tag -- alternatively a better option may be to have a way to spend a variable amount when performing the tagging action. This would be a bit similar to the `applause` feature on Medium.com

## Use cases
1. This would allow the council and governance to have a mechanism to pick videos to reward via channel payout proposals
2. This would have heavy use when it comes to content moderation in general
3. This would allow for gateways to utilize the data via specific views (for example, only following the tags that certain users have applied, or using tags that have only been applied within some specific recent time frame)
4. This would also allow for governance or the curator groups to hire people tasked with identifying certain types of videos (for example: identify videos that are of reasonable quality and not spammy reuploads from other services with poor metadata etc)