Added PLN Manager (LOCKSS) stubs

refs #5425

Added a Space class for the PLN Manager/LOCKSS.  Functionality relating to
the PLN manager on the changes to the METS file are stubs, since those
requirements not yet decided on.

Updated store AIP and download file functions to work with LOCKSS, and
added a stub callback function for when LOCKSS is done storing the file.
Added a new status for a package for when it is on the Storage Server, but
not yet in LOCKSS.
Rename PLN manager to LOCKSS-o-matic
Update LOCKSS-o-matic fields
Change LOCKSS download URL

refs #5425

Split chunks of an AIP are found at <aip_uuid>/download/<chunk_number>/
now, instead of the chunk number being passed as a GET parameter.
LOCKSS Space can parse service document

Add function to fetch and parse a service document, update the au_size and
collection_iri.  Added dependency on sword2 client library.
Minor fixes

Fix sword2 version, add ipython as a development dependency, and add a
common namespace map for use when working with METS and XML.  Update
existing lxml code to use it.
Create AtoM entry for AIP

refs #6009

Create the AtoM entry with the title, ID, and description of the AIP.
Title and description parsed from the METS file Dublin Core title and
description.  Extract state IRI for polling LOCKSS-o-matic from the
deposit receipt.
Update LOCKSS-o-matic service doc and resource creation

refs #6009

Update LOCKSS handling of service document and atom entries to create
resources to match API changes.

Add checksumType parsing to service document.  Resource creation uses
lom:content tags, add checksum and checksum type to content tags.

Code moved to LOCKSS Space from Package, since it deals more with
Space-specific problems than Package.
LOCKSS WIP - edit & state IRI

refs #5425

Properly parse the edit and state IRIs from the deposit receipt.  Add sword
and Lockss-o-matic related namespaces to the namespace map.  Start on
polling for state, comments and logs where work needed.
Initial LOCKSS tests

Add pytest and pytest-django as testing dependencies.  Add testing fixtures
- initial data needed for everything, and a lockss-o-matic specific one.
Start on adding tests; currently only work if the modified simple sword
server is running.
Update for LOM changes

refs #5425

Update namespace for LOM, and make common.utils the only place it is
defined.  Add content provider ID, input by the user, and used to identify
the SS to LOM.
File splitting for LOCKSS uses tar

refS #5425

Splitting the file into chunks of no more than au_size uses tar instead of
split.  A tar file has headers and stores some of its own metadata, making
it a safer choice.
Update Lockssomatic to use new infrastructure

refs #5425

Update Lockssomatic to use (post) move to/from storage service.  Removed
now duplicate _store_aip_lom.  Store AIP calls post move functions.
Sizes to/from LOM are in kB

refs #5425

maxUploadSize in the service document, and lom:content size in the atom
entry are both in kilobytes, while all internal sizes are stored in bytes.
Add unit conversion.  Outgoing size rounded up.