Heroku review apps: memory issue

[Matt-Butler]

When loading the review apps, we see this page:

This is due to the webpack-dev-server taking up too much memory.

[Matt-Butler]

We might want to create the static assets and host them on heroku to get around the memory issue.

[windse7en]

Heroku Error R14(Memory quota exceeded): https://gist.github.com/windse7en/e9685f48af1b015ff1245c68297985bc

[windse7en]

Heroku logs after updating express: https://gist.github.com/windse7en/b5b0df051286df8970a83c0f3ebfc4e3

After using built assets and express server, we get rid of most of the R14 error. But there are still some R14 errors. That dues to the webpack compile process taking too much memory.

[windse7en]

In the #326, move the build process into heroku postbuild. It will run for any new commit and won't have the memory issue in the build process. All the build logs information can be found in the Heroku dashboard.

[windse7en]

Close this memory issue. As we move the build process into the heroku build time, there is no memory issue in the logs.