Allow java not be installed

tasks/install.yml

@@ -1,6 +1,7 @@
 ---
 - name: Install OpenJDK
   apt: name=openjdk-{{java_version}}-jre-headless state=present
+  when: java_version != 'none'
 
 - name: Fetch kafka binary package
   get_url: dest="{{ kafka_tarball_location }}/{{ kafka_tarball_name }}" url="{{apache_mirror}}/kafka/{{kafka_version}}/{{kafka_tarball_name}}"