Add Hamcrest as a dependency for ant
We need a modern bouncycastle; update the ant dependencies
We need JUnit4; update the ant dependencies
Fix bug #6422

Set the manifest's classpath for the runtime environment rather than
 the build environment. One should be able to start freenet using
 "java -jar freenet.jar" or double-clicking it
Drop Main-Class and Class-Path from the manifest

The rationale is that we can't pass parameters to the JVM and
 they do more harm than good (starting the node with 64M of RAM
 is a terrible idea).