Update kredits-contracts and ethers.js

This uses the new ethers.js 4.x API which is required by the new
kredits-contracts.
Also Operator is now Proposal in the new kredits-contracts wrapper

package.json

@@ -15,7 +15,7 @@
     "lint:js": "eslint .",
     "start": "ember serve",
     "test": "ember test",
-    "start:local": "NETWORK_ID=100 WEB3_PROVIDER_URL=http://localhost:7545 ember s",
+    "start:local": "WEB3_PROVIDER_URL=http://localhost:7545 ember s",
     "build": "ember build",
     "build-prod": "ember build --environment production",
     "update-version-file": "bash scripts/update-version-file.sh",
@@ -54,7 +54,7 @@
     "ember-source": "~3.8.0",
     "ember-truth-helpers": "github:jmurphyau/ember-truth-helpers#31a14373a31f1f82c77537720549b47a95c28e5f",
     "eslint-plugin-ember": "^5.2.0",
-    "ethers": "3.0.15",
+    "ethers": "^4.0.27",
     "kosmos-schemas": "^1.1.2",
     "kredits-contracts": "^3.x",
     "loader.js": "^4.7.0",