Support Drush > 5.3

I didn't make a note of what the conflict was, so I have installed devel 5.3.1 locally and will look out for problems.

Problem was the devel generate base class, but it has now been resolved.
In HEAD there is no longer a conflict with devel module.

The conflict line is still there in composer.json, but looks like you're still working on this.

oops I had just removed it from mcapi.info.yml

Ok that worked.