Add initial exchange contract function, set up web3Wrapper, added types and utils

src/ts/types.ts

@@ -0,0 +1,30 @@
+import * as _ from 'lodash';
+
+// Utility function to create a K:V from a list of strings
+// Adapted from: https://basarat.gitbooks.io/typescript/content/docs/types/literal-types.html
+function strEnum(values: string[]): {[key: string]: string} {
+    return _.reduce(values, (result, key) => {
+        result[key] = key;
+        return result;
+    }, Object.create(null));
+}
+
+export const ZeroExError = strEnum([
+  'CONTRACT_DOES_NOT_EXIST',
+  'UNHANDLED_ERROR',
+  'USER_HAS_NO_ASSOCIATED_ADDRESSES',
+]);
+export type ZeroExError = keyof typeof ZeroExError;
+
+/**
+ * Elliptic Curve signature
+ */
+export interface ECSignature {
+    v: number;
+    r: string;
+    s: string;
+}
+
+export interface ExchangeContract {
+    isValidSignature: any;
+}