Fixes gh-1205

Also added descriptions to properties.

fixes gh-1131

For compatiblity with Angel streams we only need to set the content
type explicitly.

Fixes gh-873

This move should be transparant to users of spring-cloud-starter-eureka.

fixes gh-579

Move turbine/hystrix amqp specific implementations to spring-cloud-stream based implementations and let the user decide which broker to use.

fixes gh-545