AMQP-330: fix JavaTypeMapper JsonArray conversion

Since `JsonMessageConverter` (`Jackson2JsonMessageConverter`) uses
`JavaTypeMapper`(`Jackson2JavaTypeMapper`) it should correctly do
a conversion around simple Java and arrays (`String[]`) too.
Seeing Jackson's `ArrayType` is **ContainerType**, erenow `JavaTypeMapper`
implementation added to `Properties` '__ContentTypeId__' header
on `toMessage` call and tried to create a collection (not array) from that header
on `fromMessage` call.

Add checks that provided **ContainerType** is (not is) **ArrayType**

JIRA: https://jira.springsource.org/browse/AMQP-330