Provide testing coverage for the is_zip and unzip methods of the StructureDirectory class in the structure_directory.py module

[brettvanderwerff]

This would be a good issue for someone new to testing. These two methods are new and need some tests. This might require some research, but we have a handful of other tests written that can serve as some form of example. is_zip should be pretty straight forward. unzip might be a little tougher and might require a dummy zip file, but again this might require some research.

I wrote these methods and intentionally left them untested for any newcomers that want to try and dig into the project. I'll leave this issue open for a day or two, if no one takes it I will happily take the issue and write the tests.

[brettvanderwerff]

I am placing this issue on the backburner, there might be some changes to the project that preclude the need for a template unzipping function