Linux fixes

-Copy PropertyChanged.Fody.dll to Tools/Fody in MediaBrowser.Model.csproj
-Check if root for WebSocketServer.FlashAccessPolicyEnabled (port < 1024)
-Check resolution value !=0 before SetResolution
-Catch _userManager.RefreshUsersMetadata exception when running MB3 for the first time
-Fix _appHost.Init() missing argument
-FFmpeg: set default and execute permission(766) to ffmpeg and ffprobe
-FFmpeg: Detect the OS type and download the correct version 
-Rename MediaBrowser.WebDashboard/dashboard-ui/scripts/Itemdetailpage.js to itemdetailpage.js