Blender 2.78c is shipped with a version of the io_blend_utils module that doesn't have a `pythonpath()` function yet, and that's bundled with an older version of BAM. To work around this, we ship BAM as wheel, and detect whether this version is needed to run. As an added bonus, Blender 2.78c can now also use the file exclude filter for Flamenco. The `bam_supports_exclude_option()` function is thus no longer necessary.