merge eslint-plugin-better rule into eslint-plugin-fp

[graingert]

currently eslint-plugin-better has a few extra rules, would be good to get one package maintained in one place rather than relying on eslint-config-cleanjs

[nickmccurdy]

Fortunately both the projects use the MIT license, which should make this easier. I just opened idmitriev/eslint-plugin-better#4.

[graingert]

@jfmengels ^