Download Support (#298)

* Implemented the ability to download files (series, volume, chapter)

* Added RBS checks to ensure user is either an admin or has download role

* Added the ability to change a users feature RBS. Changed the Role seed to use reflection

API/Services/DirectoryService.cs

@@ -102,6 +102,16 @@ namespace API.Services
           return !Directory.Exists(path) ? Array.Empty<string>() : Directory.GetFiles(path);
        }
 
+       /// <summary>
+       /// Returns the total number of bytes for a given set of full file paths
+       /// </summary>
+       /// <param name="paths"></param>
+       /// <returns>Total bytes</returns>
+       public static long GetTotalSize(IEnumerable<string> paths)
+       {
+          return paths.Sum(path => new FileInfo(path).Length);
+       }
+
        /// <summary>
        /// Returns true if the path exists and is a directory. If path does not exist, this will create it. Returns false in all fail cases.
        /// </summary>