Github Actions CI Setup

[ltfschoen]

Currently Travis CI setup fails with this error https://travis-ci.org/DataHighway-com/node/jobs/648909043.

Alternatives to try include:
https://github.com/centrifuge/centrifuge-chain

[ltfschoen]

This issue may go away when we update this repo to use a more recent version of Substrate, since at the moment we're using rev 47b158b7a04bf0f5cd542a468076a7fda29648a4

[ltfschoen]

We're using Github Actions for CI instead of Travis CI.

[ltfschoen]

We need to resolve #27, #28, and #29