passing string as total throws

[thebigredgeek]

This is probably an idiotic error on my part, but it seems like passing an environment variable into "total" is a totally (wink) legit use case and it would be great if progress would parseInt the total option so I didn't have to do it myself?

[thebigredgeek]

@tj you want me to add a typecheck, a more descriptive error, and docs?

[tj]

👍 SGTM. added you as a collaborator and npm, I'll move this over to visionmedia/* since it's community maintained