* process pdf and xml file lists

* allow sub directories in output path

* make output_annotated_images_path relative to output

* make sure that output directory is created

* use write_bytes in favour of explicit makedirs (cloud ready)

* make --pdf-base-path required

* added pipeline

* not extending ABC due to serialization errors

* log pipeline options

* added test to check serialization

* changed super import to avoid one of the serialization errors in Dataflow

* moved most functionality to separate module

* added libgl1 to setup.py

* added PreventFusion

* minor import grouping

* added TransformAndCount

* reverted super __init__ call

* use parse args, not ignoring unknown args

* expose all of the worker arguments