[Console] update 3rd party executables button

[grolschie]

Hi. My suggestion is that there could be a button in the console to check for and download updated 3rd party executables that might be hosted on your server (for bug fixes), such as ffmpeg.exe, etc. That would be a nice easy way to get an updated ffmpeg.exe without waiting for the next release of Serviio or having to do it manually. Thanks for your consideration.