see readme for the changelog details, bump to 1.8.0

This is basically a PR for Issue #2 that I just opened yesterday.
It adds both the features I asked for, plus I added a second save button to the top of the form for quicker access and one more css example so it is easier to make the design a bit more neutral.
I haven't don't extensive testing yet, but it will go live on one a blog tomorrow.
Btw, I also added a default-icon if there is no featured image. It is licensed under CC0 (http://creativecommons.org/publicdomain/zero/1.0/) so should hopefully be no issue.
If you think anything should be changed/improved just let me know and I'll do my best.