Add new table author_institution_aliases

This table will be used to disambiguate homonyms
by using an institution name as context. The assumption,
which might prove wrong, is that no two authors have had
the exact same name associated with the exact same
institution name.

Related issues: #18 and #61
https://github.com/medea-project/ipcc-database/issues/18
https://github.com/medea-project/ipcc-database/issues/61
Record author+institution aliases for homonym 'William Collins'

Related issue: #18
https://github.com/medea-project/ipcc-database/issues/18