creating streamcorpus_pipeline/_rmtree.py and matching tests for
verbose logging and fallback when shutil.rmtree fails because
something is left behind in tmp_dir_path.  Individual stages must not
hang on to open files, otherwise some file systems, e.g. NFS and
Windows, will prevent full removal of tmp_dir_path:

https://uisapp2.iu.edu/confluence-prd/pages/viewpage.action?pageId=123962105
adding `rmtree` as a thing exposed by streamcorpus_pipeline.util
explicitly calling pipeline.cleanup() after using a pipeline
in both streamcorpus_pipeline/{run,_rejester}.py
moving the naming of this process's tmp_dir_path into
normalize_config, so that all stages and Pipeline itself get the same
subdir within the config files tmp_dir_path, which will be shared
across many processes possibly on the same file system:

This is in normalize_config now, instead of only in Pipeline
+    # ensure that tmp_dir_path is unique to this process, so Pipeline
+    # can remove it and anything left in it by various stages.
+    config['tmp_dir_path'] = os.path.join(config['tmp_dir_path'], uuid.uuid4().hex)
+

also explicitly closing the temp chunk file when it has no data,
because otherwise it stays open and prevent Pipeline.cleanup from
finishing:

-        if self.t_chunk:
+        ## bool(t_chunk) is False if t_chunk has no data, but we still
+        ## want to make sure it gets closed.
+        if self.t_chunk is not None:
             self.t_chunk.close()
fixing file name for test data file
renaming _cleanup() to cleanup()
repairing tests that were pointing at uncompressed versions of test data files