Adds new featured image for "Upgrading Fedora 26 to Fedora 27" article
@ryanlerch, I botched this one with the rounded corners on the F27 wallpaper and the number 7 in 27. I have a hard time figuring out where to look and read to do the things properly. I'd appreciate your feedback so I can do this correctly in the future.
rebased onto 5fda4ff