v0.4.1

Now includes contract address files for both SCD and MCD. Set mcd in plugin options to switch to the latter:

await Maker.create('http', {
  plugins: [
    [GovPlugin, { mcd: true, network: 'kovan' }]
  ]
})

Also, will now always override the dai.js contract address for GOV with the one found in its own address file.