Move the check that a GLMObject has a class to the initialize method, so we can be sure it has a class regardless of how it was created (from a file or a manual property list).  Ideally we could also get rid of the check for a class in GLMObject#to_s, but we don't currently have any guarantee that the :class wasn't removed from the object after it was created.
Move the check that a GLMObject has a class to the initialize method, so we can be sure it has a class regardless of how it was created (from a file or a manual property list).  Ideally we could also get rid of the check for a class in GLMObject#to_s, but we don't currently have any guarantee that the :class wasn't removed from the object after it was created.

mactyr/glm-wrangler