A patch patch from Pierre smits for 
"include ivy clearcache in build" https://issues.apache.org/jira/browse/OFBIZ-5461
"build.xml includes both namespace for Apache Ivy and ivy-init target" https://issues.apache.org/jira/browse/OFBIZ-5462

jleroux: I added activemq (recently added) in the clean-downloads target



git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1556166 13f79535-47bb-0310-9956-ffa450edef68