foris: make sure that locale folder is present

HomerSP found that locale folder is not present and it was caused by this commit https://gitlab.labs.nic.cz/turris/turris-os-packages/commit/5688505a71381d59169b1310903466957ef28975. When the folder is not present it throws error 500. This PR fixes issue when users don't have any other localization than English.

I compile tested it in branch "master". Locale folder is present and in the folder, there is only one file .keep without any other folders or files.

Fixes: turris/foris#163