tmp: fix for elsevier outside scoap3
Elsevier: article date taken from issue.xml
Elsevier: no pdf and fix

* Adds support for usage outside SCOAP3 - no PDF.
* Fixes MissingPDFError.
Elsevier: date and journal name fixes

* Gets jurnal name from main.xml file if it's not available in
  issue.xml.
* Fixes pulication date for references.
Springer: fixes for changes in delivered files

* Changes files names.
* Changes recognising the papaer journal.
* Fiexes copyright and keywords extraction.
* Changes XML an PDF adding.

Elsevier: reporting error change.