Issue with capitalization of German translation files

From #2351858-zen:

> The translation file of this plugin and some other plugin of yours does not work, e.g. de_DE.
> After a log of time and research I found the reason of this issue.
> Suffix of some files to download, e.g. https://wpjobmanager.com/wp-content/uploads/2017/08/application-deadline-german.zip
> do have capitals ".MO"! On linux based web servers this does not work, because in your code your load_text_domain looks for small letters ".mo".
> I highly would appreciate if you fix this on one or the other site (suffix or PHP code).

We can probably just replace the .zip file there with `*.mo` files?