Ant should detect and remove old BASE jar files

[Nicklas Nordborg]

An annoying thing when working as a developer is that whenever the BASE version increases, there are old JAR files from the previous version laying around. Sometimes we get some strange errors and behavior due to class loading from the old JAR files. It would be nice if the ant script could automatically remove the old JAR files.

It should not be too difficult. Basically, we only create JAR files in two locations: www/WEB-INF/lib and bin/jar. We should remove all base-*.jar files except base-*-<current version>.jar.

[Nicklas Nordborg]

(In [7399]) Fixes #2093: Ant should detect and remove old BASE jar files