add maven.compile.source property. Needed to work under JDK 1.5.0

git-svn-id: https://svn.apache.org/repos/asf/maven/maven-1/plugins/trunk@114938 13f79535-47bb-0310-9956-ffa450edef68

java/plugin.properties

@@ -21,4 +21,5 @@
 # FIXME: Need to move these to the jar plugin
 maven.jar.manifest = ${maven.conf.dir}/Manifest.mf
 maven.jar.mainclass = 
-maven.compile.target = 1.1
+maven.compile.target = 1.1
+maven.compile.source = 1.3