support Reactor-based CF Java Client (#22)

* 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

docs/src/main/asciidoc/intro.adoc

@@ -6,6 +6,9 @@ middlware that you "bind" to an app, essentially providing it with an
 environment variable containing credentials (e.g. the location and
 username to use for the service).
 
+The `spring-cloud-cloudfoundry-commons` module configures the
+Reactor-based Cloud Foundry Java client, v 3.0, and can be used standalone.
+
 The `spring-cloud-cloudfoundry-web` project provides basic support for
 some enhanced features of webapps in Cloud Foundry: binding
 automatically to single-sign-on services and optionally enabling
@@ -14,7 +17,5 @@ sticky routing for discovery.
 The `spring-cloud-cloudfoundry-discovery` project provides an
 implementation of Spring Cloud Commons `DiscoveryClient` so you can
 `@EnableDiscoveryClient` and provide your credentials as
-`spring.cloud.cloudfoundry.discovery.[email,password]` and then you
-can use the `DiscoveryClient` directly or via a `LoadBalancerClient`
-(also `*.url` if you are not connecting to
-https://run.pivotal.io[Pivotal Web Services]).
+`spring.cloud.cloudfoundry.discovery.[username,password]` (also `*.url` if you are not connecting to https://run.pivotal.io[Pivotal Web Services]) and then you
+can use the `DiscoveryClient` directly or via a `LoadBalancerClient`.