Remove redundant else

When else statement is empty it might raise a diagnostic.

Before:

``` csharp
if (true)
{
    //some statement (not a comment)
}
else
{
}
```

After:

``` csharp
if (true)
{
    //some statement (not a comment)
}
```

Diagnostic id: `CC0089`
Category: `Usage`
Severity: `Info`

@gandarez is working on it.
