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/spec/helpers/ts_console.ts

@@ -0,0 +1,7 @@
+// NOTE (jchristie@8thlight.com) This file helps Jasmine
+// comprehend TS sourcemaps by installing a reporter
+// specifically for TypeScript
+const TSConsoleReporter = require('jasmine-ts-console-reporter');
+
+jasmine.getEnv().clearReporters();
+jasmine.getEnv().addReporter(new TSConsoleReporter());