Adopt a priority tagging system like Parity has

[danfinlay]

Parity's priority tagging system is awesome. Look at any issue for an example:
https://github.com/ethcore/parity/issues/3939

I don't get how it works, but we should try writing up a spec for that, and try adopting it, I think it could help us focus our efforts even better than Waffle does now.

[danfinlay]

I'm beginning to draft a priority system here:
https://consensys.quip.com/vMs3AJL0hgTV

[danfinlay]

Requesting feedback from MetaMask devs, once we agree on a system, we can add the tags and start adopting them.