oaiharvester: refextract task fix

* Checks properly if the PDF is downloaded successfully inside the
  refextract task.

Reviewed-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
Signed-off-by: Georgios Papoutsakis <georgios.papoutsakis@cern.ch>
template: fix for unicode url handling

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
formatter: addition of format.mime_type column

* Adds upgrade for the `Format` table by adding `mime_type`.

Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>
cloudconnector: fixes in the cloud apps

* User can succesfully connect through his google/dropbox accounts
  and manage his files.

Signed-off-by: Eirini Psallida <eirini.psallida@cern.ch>
cloudconnector: improvements and fixes

* Several PEP257 and PEP8 fixes.

* Deletes `factory.py`.

* Creates `utils.py`, `registry.py` and `manager.py`.

* Uploads a file to a cloud application.

* Uses `refresh_token` to get a new token when the token is expired.

Signed-off-by: Eirini Psallida <eirini.psallida@cern.ch>