Update eureka-client to use Delta class.
Update avro/json codecs to deal with modified data model.
Configure junit test timeouts for eureka-server tests.
Merge pull request #175 from tbak/2.x

Update eureka-client to use new domain model with Delta class.
Comment out mavenLocal()
Delta should be serializable
Adding diff methods to InstanceInfo to generate sets of Deltas
from two instanceInfos.
Removing delta tests for Long type as they are no longer a supported
delta variable type.
Test clean up with SampleDelta and SampleInstanceInfo