Enable System Properties-driven proxy configuration for Reactor Netty.

Also, upgrade to newest Reactor Netty.

Closes gh-654

pom.xml

@@ -30,7 +30,7 @@
 		<spring.version>5.3.5</spring.version>
 		<spring-data-bom.version>2020.0.5</spring-data-bom.version>
 		<spring-security-bom.version>5.4.5</spring-security-bom.version>
-		<reactor.version>2020.0.5</reactor.version>
+		<reactor.version>2020.0.13</reactor.version>
 		<java.version>1.8</java.version>
 		<project.type>multi</project.type>
 		<dist.id>spring-vault</dist.id>

spring-vault-core/src/main/java/org/springframework/vault/client/ClientHttpConnectorFactory.java

@@ -139,7 +139,8 @@ public class ClientHttpConnectorFactory {
 			}
 
 			client = client.tcpConfiguration(it -> it.option(ChannelOption.CONNECT_TIMEOUT_MILLIS,
-					Math.toIntExact(options.getConnectionTimeout().toMillis())));
+							Math.toIntExact(options.getConnectionTimeout().toMillis())))
+					.proxyWithSystemProperties();
 
 			return new ReactorClientHttpConnector(client);
 		}