Nitpicking

Mark found out a few glitches in the plugin. These two changes eliminate them.

The first commit is a bit more serious in that it will interfere with the correctness of the plugin when it's used in a certain project type, such as a Maven project. It also prevents the job configuration from getting updated programmatically (although this isn't probably too common.)

The second commit removes a rough edge where a form validation is too eager and issue a big warning where it shouldn't.