deposit: adaptation to fieldlist separation

After appling commits below to invenio. These one needs to be applied to inspire.

Invenio commits to apply:
https://github.com/kneczaj/invenio/commit/8b8990305a26806a387fb59423c4abf248982355
https://github.com/kneczaj/invenio/commit/8b8990305a26806a387fb59423c4abf248982355
https://github.com/kneczaj/invenio/commit/7fd70abd1bb59b5c95879d0f9879cde75073564c
https://github.com/kneczaj/invenio/commit/e5b04a3146cf62384eae55bcd4142212436ebcd9

Our sprint-2 branch commit, which is incompatible - to remove:
https://github.com/jmartinm/invenio/commit/d7d8dd804c7911afc23501fa700d0ac60f543377