Release version 15.0.0

* detection of binary files in `dump_file` and their dump in base64
  encoding instead of direct inclusion
* call to `hwinfo` in lshw module

* `firmare_devices: not found` error in `firmware` module
* red herring SSL error in `turris-webs` module
* missing a module name in headers

* packages: limit updater keys we query to `/etc/updater/keys/*.pub`
  thus ignoring the `*.pub.sig` files that are also stored there.
* `Makefile` used to manage translations was improved.