Change implementation of SerializedTaskInvoker to be non-blocking.
Merge pull request #257 from qiangdavidliu/2.x

Simple system property settings for both registration and discovery heartbeats, for client and server.
[Gradle Release Plugin] - pre tag commit:  '2.0.0-DP2'.
[Gradle Release Plugin] - new version commit:  '2.0.0-DP3-SNAPSHOT'.
Merge branch '2.x' into workspace

Conflicts:
	eureka-core/src/main/java/com/netflix/eureka2/utils/SerializedTaskInvoker.java
Minor update in eviction queue handling + related unit tests.
Add eviction queue/self preservation metrics + configuration parameters.
Merge branch '2.x' into workspace
Merge pull request #258 from tbak/2.x

2.x multiple changes