Issue #36 - Fixed the editor css overflow in the product description page.

**Important:** I have raised this PR against 1-3-stable. You may want to merge it into master as well.

In this change I also fixed the larger problem of people not realising that they have the power to configure tinymce.

I have also removed the width field because it automatically sets itself to the width of the text area that it is replacing. This is a really good default and should be the one that we use. People can customise this later if they choose to.

[Please see here for more information.][1]

 [1]: https://github.com/spree/spree_editor/issues/36#issuecomment-16006873