Adding RegistryMatcher for custom Transform Rules

When initializing the simplexmlconverter you now can add custom transform rules so that text in elements or atributes such as "Sun, 29 Sep 2013 15:26:59 +0000" can easily transformed to a Java object, be it Date, DateTime, String, Int, some custom pojo, etc.

So that in the model you dont have to write extra code to parse a the date.

```
<person>
	<name>Test</name>
	<birthday>Sun, 29 Sep 2013 15:26:59 +0000</birthday>
</person>

@Root
public class Person {
    @Element
    private String name;
    @Element
    private Data birthday;
}

// The Custom transform class to transfrom a String to Date
public class DateFormatTransformer implements Transform<Date> {
    private DateFormat dateFormat;

    public DateFormatTransformer(DateFormat dateFormat) {
        this.dateFormat = dateFormat;
    }

    @Override
    public Date read(String value) throws Exception {
        return dateFormat.parse(value);
    }

    @Override
    public String write(Date value) throws Exception {
        return dateFormat.format(value);
    }
}

// Initialize the format rule for the SimpleDateFormatter
DateFormat format = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss zzz", Locale.US);
RegistryMatcher matcher = new RegistryMatcher();
matcher.bind(Date.class, new DateFormatTransformer(format));

// Create the restAdapter with the simpleXmlConverter that uses the Custom Transformer
RestAdapter restAdapter = new RestAdapter.Builder()
                                              .setServer(SyncAdapter.SERVER_URL)
                                              .setConverter(new SimpleXmlConverter(matcher ))
                                              .build();

Person person = restAdapter.getPerson();
```