Set label colours for GitHub Issues

[rtyley]

The label colours in:

https://github.com/gu-who-demo-org/people/issues?state=open

...look quite drab (they're all grey), compared to

https://github.com/guardian/people/issues?state=open

...gu:who should set label colours appropriately if they've not been set before!

[philwills]

This looks like it's been fixed to me.

[rtyley]

I had in mind automatic label-with-correct-colour creation, like done with Prout:

https://github.com/guardian/prout/blob/7cc505268/app/lib/RepoSnapshot.scala#L227

...I don't think there's similar code in gu:who, ie there's nothing in https://github.com/guardian/gu-who/blob/df697a8/app/lib/AccountRequirement.scala that has a colour associated with it.