+ upgrade to AspectJ 1.6.8

+ externalize some of the jar versions
+ align the versions of some dependencies between pom.xml and ivy.xml

org.springframework.core/build.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project name="org.springframework.core" xmlns:ivy="antlib:org.apache.ivy.ant">
 	<property file="${basedir}/../build.properties"/>
+	<property file="${basedir}/../build.versions"/>
 	<import file="${basedir}/../build-spring-framework/package-bundle.xml"/>
 	<import file="${basedir}/../spring-build/standard/default.xml"/>
 	<target name="create.pom" depends="ivy.init, resolve">