jsonalchemy: default values for subfields

* Fixes jsonalchemy ignoring default values when the main field is
  present but not one of the subfields. (closes #34)

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
assets: fix some missing url_for("static")

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
Reported-by: Jan Åge Lavik <jan.age.lavik@cern.ch>
collect: symbolic link storage

* Adding a symbolic link storage for developers. To enable it, put this
  to your config: COLLECT_STORAGE = u"invenio.ext.collect.storage.link"
  then run `inveniomanage collect` to create all the links from the
  static folders to the intance folder.
  NB: only files are symlinked, not folders!

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
base: deprecation of STATIC_MAP

* Deleting STATIC_MAP and all its links. All the files should be served
  from the instance_path directory via collect.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
travis: collection of the static files

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
workflows: abstraction layer for workers

* Adds an abstract class to be used like a base for
  worker wrapper.

* Implements a worker wrapper for abstraction for
  celery worker.

* Starts the implementation of a worker wrapper for
  redis worker.

* Fixes PEP8 and sphinx documentation specification.

* Fixes mistake about iteritems with six.

Signed-off-by: Guillaume Lastecoueres <guillaume.lastecoueres@cern.ch>
workflows: more unit tests

* Adds more unit tests to the workflows module, including
  new test workflows. Coverage should now be about 50%.

* Modifies API internals for unit tests conformation.

* Adds one file for tests which are using asynchronous
  worker to compute.

* Corrects unit tests.

Signed-off-by: Guillaume Lastecoueres <guillaume.lastecoueres@cern.ch>
workflows: global improvement

* Updates workflow to comply with the modification in
  tasks librairies.

* Fixes an error with the new ObjectVersion type with
  python3.

* Fixes sphinx mistakes.

* Removes useless regex.

* Fixes PEP8 mistakes.

* Adds more documentation to some functions.

* Removes useless and obsolete code, factorize some parts.

* Changes the start workflow function to give the
  possibility to start from a new clean BibWorkflowObject.

* Adds the refresh frequency as a parameter for workflows
  synchronisation.

Signed-off-by: Guillaume Lastecoueres <guillaume.lastecoueres@cern.ch>
oaiharvest: PEP8 and errors category

* Fixes PEP8 errors in a strict way.

* Allows log of errors of loglevel=40 in oaiharvest.

Signed-off-by: Guillaume Lastecoueres <guillaume.lastecoueres@cern.ch>