Merge pull request #159 from tbak/2.x

Eureka transport update.
Interests infra (WIP)
Merge branch '2.x' of https://github.com/Netflix/eureka into 2.x

Conflicts:
	eureka-core/src/main/java/com/netflix/eureka/registry/Interest.java
Update for the interests changes
Interests infra (WIP)
Interests infra (WIP)
Merge pull request #160 from NiteshKant/2.x

Initial attempt to interests implementation
Adding initial implementations to partially implemented model classes
Implementing init state & real time state consistency.

Created a special "pausable" Subject that can be used for any data set that needs a consistency between iterator creation and change notification stream.
Merge pull request #162 from NiteshKant/2.x

Implementing init state & real time state consistency.
Merge pull request #161 from qiangdavidliu/2.x

Adding initial implementations to partially implemented model classes
Switching sample notification generation in test to SampleChangeNotification
Merged EurekaRegistryImpl and InstanceRegistry, and renaming to LeasedInstanceRegistry
for better name context.
Merge pull request #163 from qiangdavidliu/2.x

Merge EurekaRegistryImpl with InstanceRegistry
Eureka transport - discovery server.
Fix avro encoding for class hierarchy.
Refactor asynchronous transport (get rid of Message hierarchy).
Eliminate type parameters from MessageBroker framework.
Fix Json codec.