Use full workspace screenshot somewhere

[skyluc]

I created a full workspace screenshot for an article. It was not used, but it exists.

I tried to find a place to put it, but I didn't come up with anything. It's best place might have been in the blog post. Too late now.

There is a whole screenshot, and a thumbnail version of it. There are currently in https://github.com/scala-ide/docs/tree/master/resources/screenshots .

If somebody has a good idea.

[heathermiller]

We could change the thumbnail of the video on the front page to be the screenshot in the background, and maybe have some text on top of it that says "Features Overview" or something similar.