message: Quick changes to fix a few missed .bundler() readme updates
  There are a few places in the readme where usage of `project.bundler()` changes were missed.  Just a simple update to the usage examples for consistency
diff: @@ -103,7 +103,7 @@ You can add splitters to any part of your build stream. We recommend using them
  ### Bundling Files
  -#### project.bundler
  +#### project.bundler()
  A stream that combines the files in your application to reduce the number of frontend requests needed. This can be a great way to [improve performance](https://developer.yahoo.com/performance/rules.html#num_http) when HTTP2/Push is not available.
  @@ -134,7 +134,7 @@ const generateServiceWorker = require('polymer-build').generateServiceWorker;
  generateServiceWorker({
  buildRoot: 'build/',
  project: project,
  - bundled: true, // set if `project.bundler` was used
  + bundled: true, // set if `project.bundler()` was used
  swPrecacheConfig: {
  // See https://github.com/GoogleChrome/sw-precache#options-parameter for all supported options
  navigateFallback: '/index.html',
  @@ -180,7 +180,7 @@ const unbundledBuildStream = forkStream(buildStream)
  // Fork your build stream to bundle your application and write to the 'build/bundled' dir
  const bundledBuildStream = forkStream(buildStream)
  - .pipe(project.bundler)
  + .pipe(project.bundler())
  .pipe(gulp.dest('build/bundled'));
  ```
  