Name displayed in help message is node-cleanup not project-cleanup

[razorheadfx]

Hi there,
thanks for making project-cleanup, I was actually on the cusp of making something similiar but it looks like you did it for me ;). So thanks for that 👍
When using it I found an artifact of it previous life as node-cleanup

https://github.com/woubuc/project-cleanup/blob/4c39244afea1b47be3dde0376dc42772ba8c2237/src/settings.rs#L9-L11

https://github.com/woubuc/project-cleanup/blob/4c39244afea1b47be3dde0376dc42772ba8c2237/src/settings.rs#L21-L23

You might want to consider using something like structopt for the argument parsing and validation (which also generates the help messages including version author etc.).