Add ``mkfake`` tool

This is an initial attempt to tackle https://trac.openmicroscopy.org.uk/ome/ticket/11070. The added logic allows for creation of a SPW structure on the file system, which (in the next iteration of work) could be analysed by the ``FakeReader`` class and imported into OMERO.

To test - build Bio-Formats, go to the ``tools`` folder and execute ``fakespw`` on the command line.