regexSearchReplace, pbCheck, formatting

I've included a quick test to see if both a copyright.html file exists and if the string 'pressbooks.com' is in one of the paragraph nodes in that file before allowing the regex to manipulate the html. I think that should be specific enough to identify if the EPUB being imported was generated from PB. It has been tested, I got plenty of sleep and I think no one will die as a result. That, and I think I finally have my IDE auto formatting the same as yours/WP friendly, so there should be no weirdness.