* Misc improvements, including fixes from @funkyfuture:
- Dockerfile: Reduces number of created layers and source contents
- Support for automatic collection creation if INIT_COLLECTION is defined
- Add entry point script docker-entrypoint.sh
- update to latest python (3.7.2 currently)
- additions to .dockerignore
- setup.py and requirements cleanup (just use plain 'gevent' requirement)
* docker-entrypoint.sh improvements:
- before running cmd, match uid/gid to that of volume dir (specified via $VOLUME_DIR, defaulting to /webarchive)
- if volume is owned by root (default if none mounted), just run as root
- if volume is owned by different user, create/update user 'archivist' to match the uid/gid of $VOLUME_DIR, then run cmd as 'su archivist'
- fully support range requests on frontend, if range request reaches pywb
- add OffsetLimitReader() to skip offset and limit read
- disbale rewriting for range requests
- serve 416 if range outside of content-length
- tests: add tests for range request handling
dockerignore: add collections/
