Use Package#getImplementationVersion to get version

The previous method (property file in the JAR) can cause problem in
classpath-sensitive environments like OSGi.

Fixes #334

Author: acogoluegnes

src/main/java/com/rabbitmq/client/impl/ClientVersion.java

@@ -15,35 +15,12 @@
 
 package com.rabbitmq.client.impl;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.Properties;
-
 /**
  * Publicly available Client Version information
  */
 public class ClientVersion {
     /** Full version string */
-    private static final Properties version;
-    public static final String VERSION;
-
-    static {
-        version = new Properties();
-        InputStream inputStream = ClientVersion.class.getClassLoader()
-                .getResourceAsStream("version.properties");
-        try {
-            version.load(inputStream);
-        } catch (IOException e) {
-        } finally {
-            try {
-                if(inputStream != null) {
-                    inputStream.close();
-                }
-            } catch (IOException e) {
-            }
-        }
+    public static final String VERSION = ClientVersion.class.getPackage().getImplementationVersion() == null ?
+        "0.0.0" : ClientVersion.class.getPackage().getImplementationVersion();
 
-        VERSION = version.getProperty("com.rabbitmq.client.version",
-          ClientVersion.class.getPackage().getImplementationVersion());
-    }
 }