New tutorials and polish (#23)

- Add / update new tutorials formatted as Juypter notbooks
- Add "scripts to rule them all" and used the `em-core` scripts as a template
- Updated and define S3 client
- Added persistent system environment variable instructions
- README Updates
- Replaced static links to original repo with dynamic links for this repo
- Improved organization
- Various markdown linting

Co-authored-by: Ryan Earley <66645596+rearley516@users.noreply.github.com>
Co-authored-by: Nadia Dimitrova <54898993+dnadia@users.noreply.github.com>
Co-authored-by: imgbot[bot] <31301654+imgbot[bot]@users.noreply.github.com>