Defaults.WithoutCodec to avoid binding collisions.

When constructing pure Dagger apps, it is hard to compose a tree that includes Defaults and GsonModule.  This is because there's a clash in Encoder/Decoder that is particularly hard to work around.  This introduces Defaults.WithoutCodec, which avoids this collision for the common case of pure-dagger use as exists in Denominator.

ex.

```java
    @dagger.Module(includes = { ReflectiveFeign.Module.class, Defaults.WithoutCodec.class, GsonModule.class, ... })
    public static final class FeignModule {
```