no space in user names, but dot, minus and underscores

Yavsc.Server/Constants.cs

@@ -6,7 +6,7 @@ namespace Yavsc
     {
         public const string ApplicationName = "Yavsc",
             CompanyClaimType = "https://schemas.pschneider.fr/identity/claims/Company",
-            UserNameRegExp = @"^[a-zA-Z][a-zA-Z0-9 ]*$",
+            UserNameRegExp = @"^[a-zA-Z][a-zA-Z0-9._-]*$",
             AuthorizePath = "~/authorize",
         	TokenPath = "~/token",
             LoginPath = "~/signin",