Typo in trace message

Hi, I was looking around the source and found a typo in one of the trace messages in UserAccount.cs. Changed from

```csharp
Tracing.Verbose(String.Format("[UserAccount.CloseAccount] called on: {0}, {0}", Tenant, Username));
```

to

```csharp
Tracing.Verbose(String.Format("[UserAccount.CloseAccount] called on: {0}, {1}", Tenant, Username));
```