I have finished my work on the "hide-toolbars-by-URL" extension and also submitted it to addons.mozilla.org (AMO). Now they review the addon and look if it's working properly. Within the next days the review process should be finished and then the addon would be visible on the addons-page.
But you can use the addon anyway because it is already available on AMO but not visible in the search-results. So to
use it you need the URL which is:
UPDATE: The link isn't working anymore. To use the add-on you will have to download and install it on your own from github.
The code is available at github: https://github.com/manuel_mauky/Hide-Toolbars-by-URLs
Within the next days I want to write some lines on how the addon works so everybody who is interested in can use the code.