Fixes Issue #2534 by setting the Application name for Linux

I followed the suggestion outlined at http://elliotth.blogspot.com/2007/02/fixing-wmclass-for-your-java.html to set the application name in Linux.  I have verified that this works for Gnome3.
@kfeuz If the implementation details change, we will notice (it states `processing-app-Base` again). For the preferred behavior you should ask @benfry.