Device icons broken on devices screen

Currently when a trailing "/" is present in the base_url it breaks device icons on the all devices page. However if no trailing "/" is used a lot of the webviews are broken. For now I've only patch the section related to the icon and attached a diff. However it is advisable that a standard is created and enforced.

I would recommend a function wrapping config import with additional helper code which checks for small things prior to continuing. One of which would be the above (no)trailing "/", if present leave, if not add. Amount other things. This would also be helpful to check the sanity of config entries where critical. But that's just a suggestion.

As stated above the problem at hand has been patched and diff attached.