MINOR: Remove <release> tag from doap file

The information from this file is displayed in:

https://projects.apache.org/project.html?kafka

I removed the tag instead of fixing it because it's one more thing to maintain and neither Hadoop nor ZooKeeper have it (httpd does though).

Author: Ismael Juma <ismael@juma.me.uk>

Reviewers: Guozhang Wang <wangguoz@gmail.com>

Closes #1378 from ijuma/remove-release-from-doap

doap_Kafka.rdf

@@ -1,8 +1,8 @@
 <?xml version="1.0"?>
 <?xml-stylesheet type="text/xsl"?>
 <rdf:RDF xml:lang="en"
-         xmlns="http://usefulinc.com/ns/doap#" 
-         xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
+         xmlns="http://usefulinc.com/ns/doap#"
+         xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
          xmlns:asfext="http://projects.apache.org/ns/asfext#"
          xmlns:foaf="http://xmlns.com/foaf/0.1/">
 <!--
@@ -12,9 +12,9 @@
     The ASF licenses this file to You under the Apache License, Version 2.0
     (the "License"); you may not use this file except in compliance with
     the License.  You may obtain a copy of the License at
-   
+
          http://www.apache.org/licenses/LICENSE-2.0
-   
+
     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -34,13 +34,6 @@
     <download-page rdf:resource="http://kafka.apache.org/downloads.html" />
     <programming-language>Scala</programming-language>
     <category rdf:resource="http://projects.apache.org/category/big-data" />
-    <release>
-      <Version>
-        <name>Kafka 0.8.1</name>
-        <created>2014-03-12</created>
-        <revision>0.8.1</revision>
-      </Version>
-    </release>
     <repository>
       <SVNRepository>
         <location rdf:resource="http://git-wip-us.apache.org/repos/asf/kafka.git"/>