promote _stages to stages
has public BatchTransform abstract class and register_stage() function
pipeline inputs_path mode for --input, iterq TaskQueue
layered configs in streamcorpus.pipeline.run
document to_local_chunks
logging and exception cleanups
s/kba/streamcorpus/
Merge branch 'master' of github.com:trec-kba/streamcorpus-pipeline
BatchTransform interface now uses process_path() instead of __call__()
make stages loading lazy to improve test performance