tests: adds new method for testing run_shell_command with xmllint
Utils: fix run_shell_command to support passing multiple args.
harvestingkit: Adds delivery/doi-to-package data

* Adds the variables packages_delivery and doi_package_name_mapping
  to springer_package.py and oup_package.py to store the time a
  package has been received and to map a doi to a package name.

Signed-off-by: Martin Vesper <martin.vesper@cern.ch>
Elsevier: fixes wrong type of argument passed to the function
tests: improve test for run_shell_command for xmllint

* Changes parameters passed to xmllint,

* Adds unpacked Elsevier DTD to tests/data and sends the path to
  xmllint as argument.
Merge pull request #98 from Dziolas/xmllint_test

tests: adds new method for testing run_shell_command with xmllint
Merge pull request #99 from mvesper/dates_aggregation_springer_oup

harvestingkit: Adds delivery/doi-to-package data
Springer: fix wrong argument for get_article function