Update to Java client 4.8.1

Fixes #54

Author: acogoluegnes

pom.xml

@@ -41,11 +41,11 @@
   </scm>
 
   <properties>
-    <rabbitmq.version>4.6.0</rabbitmq.version>
+    <rabbitmq.version>4.8.1</rabbitmq.version>
     <slf4j-api.version>1.7.25</slf4j-api.version>
     <junit.version>4.12</junit.version>
-    <mockito-core.version>2.16.0</mockito-core.version>
-    <awaitility.version>3.1.0</awaitility.version>
+    <mockito-core.version>2.21.0</mockito-core.version>
+    <awaitility.version>3.1.2</awaitility.version>
 
     <maven.dependency.plugin.version>2.8</maven.dependency.plugin.version>
     <maven.compiler.plugin.version>3.5.1</maven.compiler.plugin.version>