Some error messages verbosity improved

Common/UploadManager.cs

@@ -46,7 +46,7 @@ namespace FLocal.Common {
 			
 			string extension = filename.Split('.').Last().ToLower();
 
-			if(!allowedExtensions.Contains(extension)) throw new FLocalException("Unsupported extension");
+			if(!allowedExtensions.Contains(extension)) throw new FLocalException("Unsupported extension '" + extension + "'");
 			if(fileStream.Length > MAX_UPLOAD_FILESIZE) throw new FLocalException("File is too big");
 
 			byte[] data = new byte[fileStream.Length];

Common/dataobjects/Account.cs

@@ -190,7 +190,7 @@ namespace FLocal.Common.dataobjects {
 			if(newName.Length > 16) throw new FLocalException("Name is too long");
 			try {
 				Account.LoadByName(newName);
-				throw new FLocalException("Name is already used");
+				throw new FLocalException("Name '" + newName + "' is already used");
 			} catch(NotFoundInDBException) {
 			}
 		}

IISMainHandler/handlers/request/MigrateAccountHandler.cs

@@ -15,7 +15,7 @@ namespace FLocal.IISHandler.handlers.request {
 
 		protected override Account DoCreateAccount(WebContext context) {
 			Account account = Account.LoadById(int.Parse(context.httprequest.Form["accountId"]));
-			if(!account.needsMigration) throw new FLocalException("Already migrated");
+			if(!account.needsMigration) throw new FLocalException("Account '" + account.name + "' is already migrated");
 			string userInfo = ShallerGateway.getUserInfoAsString(account.user.name);
 			Regex regex = new Regex("\\(fhn\\:([a-z0-9]+)\\)", RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.Singleline);
 			Match match = regex.Match(userInfo);