The following configuration parameters can be passed to the importer either
in its static configuration when it is added to a repo or with an individual
sync call.

num_units : Indicates how many units should be in the repository after the sync
  completes. Units will be named incrementally following the pattern
  harness_unit_%d. If the repository previously contained more units than this
  number, the extra units will be removed as part of the sync.

write_files : If true, the importer will write an empty file with the appropriate
  name and location as it it had actually downloaded a file. If this is false,
  the metadata for each unit will still be added to the Pulp server but the
  file system will not be touched. When written, files are chunked into 5 different
  subdirectories to exercise Pulp's ability to retain the importer's requested
  relative path for a unit while determining the final storage location.

sync_delay_in_seconds : Number of seconds to wait at the tail end of the sync
  before informing Pulp the sync has completed. This can be used to simulate
  slow connections in the plugin.
