Inconsistency between classic StyleCop and StyleCopAnalyzers with SA1303

In this code:

```
public class SomeClass
{
    public void SomeMethod()
    {
        const string url = "some constant value";
    }
}
```

the classic StyleCop reports SA1303 (ConstFieldNamesMustBeginWithUpperCaseLetter) but StyleCopAnalyzers doesn't.
