refactor(serve): serve as an export and return config from its promise. (#705)

Author: jthoms1

src/index.ts

@@ -7,6 +7,7 @@ export { lint } from './lint';
 export { minify } from './minify';
 export { ngc } from './ngc';
 export { sass, sassUpdate } from './sass';
+export { serve } from './serve';
 export { transpile } from './transpile';
 export { uglifyjs } from './uglifyjs';
 export { watch, buildUpdate } from './watch';

src/serve.ts

@@ -52,6 +52,7 @@ export function serve(context: BuildContext) {
     })
     .then(() => {
       onReady(config, context);
+      return config;
     }, (err: BuildError) => {
       throw err;
     })