travis: minimal requirements testing

* Adds script for minimal requirements generation from `setup.py`.
  (addresses #2044)

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

* Adds op.has_table to upgrader for use in upgrade scripts.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
tags: initial upgrade

* Adds initial upgrade script from Invenio v1.x for tags module.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
pidstore: initial upgrade

* Adds initial upgrade script from Invenio v1.x for pidstore module.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
records: record_json table

* Adds upgrade recipe for adding table record_json in records module.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
formatter: kind column in bibfmt

* Adds upgrade recipe adding bibfmt.kind column in
  formatter module.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
messages: initial upgrade

* Adds initial upgrade script from Invenio v1.x for messages module.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
oauthclient: nullable extra_data column

* Upgrades remoteACCOUNT.extra_data column to be nullable.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>
workflows: initial upgrade

* Adds initial upgrade from Invenio v1.x. for workflows module.

Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>