Add endpoint to store scraped courses

[austinsilveria]

What's New?

• save_courses API accepts a JSON object containing a list of all scraped courses (request.form did not play nicely with lists)
• courseId is now a string to uniquely identify each course (e.g. CSC 101)
• validate_input_keys() pulled out to its own function to be reused

Fixes #46

Type of change (pick-one)

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Integration test with course scraper stores all scraped courses in local MySQL instance.

Steps

1. Ensure your local connection to MySQL
2. Clone https://github.com/calpoly-csai/csai-scraping
3. Run flask_api.py in api package
4. Run sustainer.py in csai-scraping package (optionally comment out other scrapers if you do not want them to run) (branch with updated csai-scraping)

Checklist (check-all-before-merge)

formatting help: - [x] means "checked' and - [ ] means "unchecked"

• I documented my code according to the Google Python Style Guide

• I ran ./build_docs.sh and the docs look fine

• I ran ./type_check.sh and got no errors

• I ran ./format.sh because it automatically cleans my code for me 😄

• I ran ./lint.sh to check for what "format" missed

• I added my tests to the /tests directory

• I ran ./run_tests.sh and all the tests pass

[mfekadu]

It worked for me and the code is fantastic, thank you @austinsilveria !