search: user-preffered output format

* Introduces a new parameter `of` for personal
  default output format.  (closes #1587)

Signed-off-by: Eirini Psallida <eirini.psallida@cern.ch>
Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>
legacy: oaiharvest admin import fix

* Improves PEP8 and PEP257. (PR #2194)

* Temporary fixes wrong imports. (addresses #2188)

Co-authored-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
legacy: websearch circular import removal

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
legacy: bibindex admin interface fix

* Fixes bibindex admin interface. (closes #2190)

Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
legacy: legacy admin interfaces addition

* Adds all the admin interfaces to the `/admin` page.

Co-authored-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Signed-off-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
installation: testing of development requirements

* Adds list of repositories with developement version of some of the
  most important libraries Invenio is depended on.  (addresses #2044)

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
template: deprecated blueprint_is_module function

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>