Sleazy Fork is available in English.
Shows just fullsize Image with hotkeys & without pop-ups on many image-hosting sites
There is no button to upload images there, and there are hundreds of screen-capturer softwares like this one out there. Not accepted.
But you can just add http://gyazo.com/* as user include in userscript options, it would show biggest image from there then.
Tutorial how to add excludes (same page for includes) - https://github.com/Owyn/HandyImage/blob/master/Tutorial:%20disable%20script%20for%20specific%20websites.md
Ok
Add: gyazo.com
http://gyazo.com/f3a6769545e682c12c1fedd2e09a2b2e