feat: initial implementation of ERC1046 (#933)

* feat: initial implementation of ERC1046

test/proposals/ERC1046/TokenMetadata.test.js

@@ -0,0 +1,18 @@
+const ERC20WithMetadata = artifacts.require('ERC20WithMetadataMock');
+
+require('chai')
+  .use(require('chai-as-promised'))
+  .should();
+
+const metadataURI = 'https://example.com';
+
+describe('ERC20WithMetadata', function () {
+  before(async function () {
+    this.token = await ERC20WithMetadata.new(metadataURI);
+  });
+
+  it('responds with the metadata', async function () {
+    const got = await this.token.tokenURI();
+    got.should.eq(metadataURI);
+  });
+});