Adds new two DiscoveryClient implementations that depend on native Service Discovery supported by Cloud Foundry.
CloudFoundryAppServiceDiscoveryClient uses cf-java-client and find container's index-based route (e.g. 0.billing.apps.internal, 1.billing.apps.internal, 2.billing.apps.internal).
SimpleDnsBasedDiscoveryClient simply uses DNS and resolve container's ip (e.g. 10.250.56.12, 10.254.160.118, 10.254.112.192). does not depend on cf-java-client
By default, existing CloudFoundryDiscoveryClient is chosen.
Configuring spring.cloud.cloudfoundry.discovery.use-dns=true enables CloudFoundryAppServiceDiscoveryClient.
Configuring spring.cloud.cloudfoundry.discovery.use-dns=true and spring.cloud.cloudfoundry.discovery.use-container-ip=true enables SimpleDnsBasedDiscoveryClient.
This DiscoveryClient eliminates the limitation of Turbine on Cloud Foundry and does not need Turbine Stream.
In some environments (such as in a PaaS setting), the classic Turbine model of pulling metrics from all the distributed Hystrix commands does not work.
See gh-19
* reactive Cloud Foundry Java Client
- new support for auto-configuring the reactor-based CF java client v3.3.
- reworkd the `DiscoveryClient` to depend on the standalone support.
- made the tests run conditionally based on presence of certain env vars.
fixes gh-21
