Paperetl

This release adds the following enhancements and bug fixes:

- Handle PDF parsing exceptions (22)
- Increase test coverage (23)
- Modify merge method to handle no update merges (24)
- Fix bug with JSON export (25)
- Fix bug with study model training (26)

This release adds the following enhancements and bug fixes:

- Add file name as source for file process (12)
- Use XML id for file figure processing (13)
- Filter duplicate ids (14)
- Build test suite (15)

This release adds the following enhancements:

- Support recursive directory processing (7)
- Improve publication date parsing (8)
- Added incremental database updates (10)
- Remove citations (11)

Minor README update to note package can be installed from PyPI

Release addresses the following:

- PDF Extraction Improvements (1) - extract additional fields from TEI XML files generated via GROBID
- Fix Windows Install issues (2)

Initial release of paperetl, migrating ETL logic from existing [cord19q](https://github.com/neuml/cord19q) project.