Show the advanced settings if they exist

When troubleshooting builds, it's really annoying to find out that a hidden "advanced" setting was messing things up. This shows the advanced fields for Ant projects that have such settings.

I freely admit that I don't know if this is idiomatic jenkins plugin writing, but this issue has annoyed me so many times that I thought I'd send in a pull request to see what happens.

Let me know if you want the change written differently.