Add contracts to packages, fix most linting errors

packages/contracts/globalsAugment.d.ts

@@ -0,0 +1,19 @@
+import {BigNumber} from 'bignumber.js';
+
+// HACK: This module overrides the Chai namespace so that we can use BigNumber types inside.
+// Source: https://github.com/Microsoft/TypeScript/issues/7352#issuecomment-191547232
+declare global {
+    // HACK: In order to merge the bignumber declaration added by chai-bignumber to the chai Assertion
+    // interface we must use `namespace` as the Chai definitelyTyped definition does. Since we otherwise
+    // disallow `namespace`, we disable tslint for the following.
+    /* tslint:disable */
+    namespace Chai {
+        interface NumberComparer {
+            (value: number | BigNumber, message?: string): Assertion;
+        }
+        interface NumericComparison {
+            greaterThan: NumberComparer;
+        }
+    }
+    /* tslint:enable */
+}