There's a few classes in the structure module that depend on service http://source.rcsb.org, that is now obsolete. They also cause test failures often, so this would help with #606.

As part of that it'd be a good idea to remove dependency on other RCSB REST APIs (at rcsb.org/pdb/rest) that are going to be deprecated.

This would be a breaking change that should go with a new major release.

It would also require updating the biojava tutorial in some places: https://github.com/biojava/biojava-tutorial/blob/master/structure/lists.md