PhoneticTokenFilter.cs - Added replace and encoder JSON properties

Looks like encoder and replace props are missing: https://github.com/elasticsearch/elasticsearch-analysis-phonetic/blob/master/README.md

Including this makes subclassing superfluously.

Sample usage:
```csharp
var settings = new IndexSettings();

settings.Analysis.Analyzers.Add("phoneticanalyzer", new CustomAnalyzer() { Tokenizer = "standard", Filter = new string[] { "standard", "lowercase", "metaphonetf" } });

settings.Analysis.TokenFilters.Add("metaphonetf", new PhoneticTokenFilter() { Encoder = "doublemetaphone", Replace = false });
```