v.0.0.3 Sync error handling, activate version, documentation (#2)

v.0.0.3 Sync error handling, activate version, documentation (#2)

* v.0.0.2 schema and sync changes

Change number json schema to anyOf with multipleOf; skip empty rows; move write_bookmark to end of sync.py

* v.0.0.3 Sync activate version and error handling

Update README.md documentation. Improved logging and handling of errors and warnings. Better null handling in Discovery and Sync. Fix issues with activate version messages.