Oxford: fix for unpacking method

* Fixes checking if variable exist in the oup_packege object.
Merge branch 'oxford'
ftp_utils: download directory fix

* moving to the corresponding ftp directory before downloading
  the files gets rid of the need to manage two different file
  names.

Signed-off-by: Martin Vesper <martin.vesper@cern.ch>
Merge pull request #56 from mvesper/fix_download_directory

ftp_utils: download directory fix
springer_crawler: fix bad print statement
2nd try for content spread over several html-pages
Merge https://github.com/inspirehep/harvesting-kit into springer