Added small check for IntegrityError in inserting a new group. It could be that because of concurrency while the group is inserted, another connection have already inserted it.
Added small check for IntegrityError in inserting a new group. It could be that because of concurrency while the group is inserted, another connection have already
inserted it.

inspirehep/invenio-accounts,inveniosoftware/invenio-accounts,inveniosoftware/invenio-accounts,tiborsimko/invenio-accounts,inspirehep/invenio-accounts,inveniosoftware/invenio-accounts,inspirehep/invenio-accounts,tiborsimko/invenio-accounts,tiborsimko/invenio-accounts