Reorganise Large Test Files in Git

[markmcdowall]

There are several test files in the repo that are rather large. These should get moved to an external housing solution.

Git LFS was a potential, but with the limited bandwidth options this causes issues with the integrated testing.

Once the files are removed it would be worthwhile cleaning the history of the files so that they are not included in the repo. It would also be necessary to automate acquiring the files for local testing during development and when using TravisCI.