Feature/circleci cache node modules

[azerella]

The CI/CD pipeline from feature/zdt-test brach doesn't have caching functionality, despite it being supported. The caching support provided by CircleCI is limited as of 09/18:

• No support for save_cache key path globbing.
• No support for multiple checksums as key names
• No support for checksum on directories
• Cannot export {{ .ENVIRONMENT.variableName }} using an eval expression such as $(ls)

This PR is a temporary workaround to enable caching. It will require the user to run the md5sum command listed in CONTRIBUTING.md anytime a new module is installed or modified assuming checksums of the package-lock.json

Quick caching tests show:

• With cache: ~7 mins
• Without cache: ~12 mins

[alex-page]

I am going to add this to the icebox until circleci updates how this works. Currently we have a lot of processes to follow when deploying and I don't want to add another just yet.

Another option is moving to yarn with something like bolt. That would make this process a lot easier.

[azerella]

Closing this in favour of #603.

Using yarn with a single hoisted node_modules folder makes circleci caching way easier 💯