ensure ARCHIVA_BASE works in 1.3.x branches see http://svn.apache.org/r1563760
 updated antrun plugin to make it works

git-svn-id: https://svn.apache.org/repos/asf/archiva/branches/archiva-1.3.x@1585541 13f79535-47bb-0310-9956-ffa450edef68