[References] Allow to reference existing objects with non-numeric PKs
[References] Allow to reference existing objects with non-numeric PKs

Some entities have non-numeric PK, like currency (USD,BRL..), with this fix now we can do this:

Acme\AcmeBundle\Entity\Payment:
  payment{1..10}:
    currency: BRL
    amount: 10

Thanks.
ma-si/alice,theofidry/alice,jewome62/alice,bendavies/alice,ogizanagi/alice,nelmio/alice,NiR-/alice,theofidry/alice,idr0id/alice,enumag/alice,meyerbaptiste/alice,PedroTroller/alice,Soullivaneuh/alice,mushkin-v/alice