Seperate out clean so it doesn't rely on pandas/dask

[meyerovb]

Banging my head for hours cause AWS Lambda has a 250mb code limit and all I wanted to do was clean email addresses. I'd have to build a damn docker image to run 10 lines of code. So instead I'm ripping out _format_email from clean_emails.py to just run it against my emails. It would be great if the actual CLEANING code was separated out into different files that don't need to import all the other nonsense that has nothing to do with CLEANING DATA.