jsonalchemy: default values for subfields

* Fixes jsonalchemy ignoring default values when the main field is
  present but not one of the subfields.

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

* Adds 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.

* NOTE: 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>
docs: documentation for collect during INSTALL

* Adds the `inveniomanage collect` step to the INSTALL documentation as
  it's now required.

* Renames INSTALL to INSTALL.rst.

Signed-off-by: Yoan Blanc <yoan.blanc@cern.ch>
script: registry usage for managers

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
script: refactoring of manager loading

* NOTE enables `inveniomanage clean` command.

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
collect: bugfix to not symlink yourself

* Removes the destination folder from the list of folder to read from.
  The destination folder is also the application static_folder so it be
  unset before running the collect operation.

* Ignores the existing files in the output log of the command and
  showing only the one added, with a nice counter at the end.

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