Add Postgraphile subscription exposure

- Add automation for TypeScript project build and tests via
  Webpack, tsc, and Jasmine
- Add custom Express application to serve Postgraphile
  subscription endpoints
- Add automated test suite for subscription endpoints

postgraphile/webpack.config.js

@@ -0,0 +1,20 @@
+module.exports = {
+  entry: "./src/index.ts",
+  mode: "production",
+  devtool: "source-map",
+  target: 'node',
+  output: {
+    filename: "vulcanize-postgraphile-server.js",
+    path: __dirname + "/build/dist/",
+    publicPath: "build/dist/"
+  },
+  resolve: {
+    extensions: [".ts", ".tsx", ".mjs", ".js", ".json", ".css", ".png"]
+  },
+  module: {
+    rules: [
+      { test: /\.ts$/, loader: "awesome-typescript-loader" },
+      { enforce: "pre", test: /\.js$/, loader: "source-map-loader" }
+    ]
+  }
+};