Deploy with auto build (mars#156)

* Use Node buildpack‘s auto build

* Remove NODE_ENV=development workaround since Node buildpack installs devDeps for build & auto-runs build.

* 📚 link to Dev Center for Node.js build customization

* Switch to new Node auto build behavior ahead of release

* Upgrade to "Node auto build" release version of inner buildpack

Default routing (mars#145)

Runtime vars compatibility with split bundles (mars#133)

* Runtime vars compatibility with split bundles

* 📚 split bundle compatibility

* Upgrade inner buildpack for split bundle compatibility

📚 notices about CRA 2 incompatibility

Support dyno metadata during build (mars#129)

Update README with latest release tag (mars#126)

Update README with latest release tag

Support for custom bundle location via `JS_RUNTIME_TARGET_BUNDLE` (ma…

…rs#117)

* Support for custom bundle location via `JS_RUNTIME_TARGET_BUNDLE`

* 📚 about custom bundle location

* 📚 how to unset custom bundle path

* Upgrade to inner buildpack with improved custom bundle UX

Support for npm Private Modules (mars#96)

📚 fix typo

📚 revs to Proxy & Testing sections