Change references to JMSSerializer concrete class to interface

[smoorhouse11]

I ran into trouble with the type hinting when using JMSSerializerBundle. I think using these interfaces as type hints should solve the problem. Using jms/serializer 0.11.0 and jms/serializer-bundle 0.10

[thewilkybarkid]

Sounds like the problem is actually a version mismatch. You'll need to use jms/serializer-bundle 0.11 or newer (this is when the serializer part was extracted into a separate package). I'll add a note to state this constraint.

You're right about the interface generally though, the references here to JMS\Serializer\Serializer should actually be to JMS\Serializer\SerializerInterface (as they are in the JMSSerializerAwareCommandInterface).

[thewilkybarkid]

Interface references introduced in 1317f686ec401119b5c9513bf1ea37300c51492d