Eureka client transport update.
Integrate registration protocol transport with EurekaService API.
Merge pull request #169 from qiangdavidliu/2.x

Initial proposal for DeltaInstanceInfo
Merge #171 with 2.x latest commit.

Conflicts:
	eureka-server/src/test/java/com/netflix/eureka/server/transport/registration/protocol/asynchronous/AsyncRegistrationServerTest.java
Merge pull request #171 from tbak/2.x

Integration of registration protocol with EurekaServerService API