Elsevier: harvesting fixes

* Fixes extracting package.
* Fixes creating pdf FFT tag.
OUP: several fixes

* Converts missing old style print functions to print().
* Changes return in extract_package function.
* Changes some typos.
* Fixes unchanged missing nlst function to new ls.
edpsciences_package: adds new module

* Converts the metadata from edpsciences
  to marc xml.

Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
pos_package: various fixes

* Fixes author name capitalization.

* Removes unused functions.

Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
tests: unit test suite added

* Adds unit tests for PoS, APS, CONSYN and EDP Sciences.

* Unifies the harvesting of EDP Sciences and APS.

Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
jats_package: new module for jats parsing added.

Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
edpsciences_package: convertion fixes

* Adds 980__a:ConferencePaper.

* Adds reference numbers.

* Adds licence harvesting.

* Removes footnotes from title and places
  them to 500__a field. Adds subtitle harvesting.

* Adds subject harvesting.

* Adds keywords harvesting.

* Adds harvesting of article type and only converts articles
  with types 'research-article', 'introduction', 'letter'.

Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>