Switch over to Lerna + Yarn Workspaces setup for a mono-repo approach

packages/0x.js/test/utils/chai_setup.ts

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+import * as chai from 'chai';
+import * as dirtyChai from 'dirty-chai';
+import ChaiBigNumber = require('chai-bignumber');
+import chaiAsPromised = require('chai-as-promised');
+
+export const chaiSetup = {
+    configure() {
+        chai.config.includeStack = true;
+        chai.use(ChaiBigNumber());
+        chai.use(dirtyChai);
+        chai.use(chaiAsPromised);
+    },
+};