Added jrEmbed TinyMCE popup to add Hello World from text editor

Added jrEmbed TinyMCE popup to add Hello World from text editor

Another commit adds text to the icon.png, and removes hello.php which is no longer in use.

Got the "We can’t automatically merge these branches. Don't worry, you can still submit the pull request. " warning from github, not sure why it won't merge automatically this time, maybe because of the removed file?