Setup GitHub Actions for deployment

## Objective
Support progress toward the [Deploy REST API ...][1] milestone by _automating the deployment step of our software development life cycle_

## Key Results
- [x] Commit _a GitHub action that deploys our dev branch to Heroku_ by _Jan 19 2020_
- [x] Commit _a GitHub action that deploys our master branch to Google Cloud Platform (or CSL server)_ by _Jan 19 2020_ **this might be hard** and it might be easier to manually deploy master branch else we could keep it all on Heroku

## Details

**Describe alternatives you've considered**
alternative is manual deployment, which would be inefficient

**Additional context**
N/A

[1]: https://github.com/calpoly-csai/api/milestones