pos_package: changes to digest enriched instead of standard DC

[fschwenn]

• To use the SISSA metadata in their enriched Dublin Core format tags had to be renamed and routines to read and write affiliations had to be added.

Signed-off-by: fschwenn florian.schwennsen@desy.de

[jalavik]

@fschwenn The tests are failing as the sample PoS XML is still in the old format. Can you also replace harvestingkit/tests/data/sample_pos_record.xml with: https://gist.githubusercontent.com/jalavik/7075497d58016bbf258f/raw/6e1d9852673a0a5db6810021308959e3db02355c/pos_example.xml and re-push?

To update this pull request after amending the file, just:

git commit a --amend
git push remotegithubname posenriched -f  # to force update your commit here

To run the tests locally:

python setup.py test  # from the root directory of the repo

[jalavik]

Superseded by #116