In this changeset, I added composite contraints on models that
were currently subject to an implicit uniqueness.
This composite constraint takes as an input the name and the deleted
columns.
The 'deleted' column is 0 by default and is updated with the value of
the associated 'id' column upon soft deletion.
What this means is that this composite constraint guarantees the fact
that we can hold many soft deleted records holding the exact same name.
Indeed, the value of the deleted column will be different whilst
forbidding 2 non-soft deleted records with the same name as their
associated 'deleted' value will be 0 and subsequently violates the
constraint.
Change-Id: I3ee39e23aa4ca9bc6b4ea9af8c6b7e6d67af0136