Document custom error body deserialization exception.

This is a less-than-ideal API but the behavior can't be changed because it's public API. We'll make error handling more robust in future versions.
Bump RxJava version.
Bump Guava dependency.
Bump Jackson dependency.
Bump Wire dependency.
Bump AssertJ dependency.
Merge pull request #623 from square/jw/document-exception-behavior

Document custom error body deserialization exception.
Use the annotations directly for parameter handling.

Before we attempted to normalize the parameter annotations into a name and type model. The introduction of multi-part transfer encodings required something more expressive so the annotation instances themselves were used. This change removes the name and type in favor of using the annotation for everything.

Deprecate the pre-encoded annotations in favor of boolean fields on the corresponding 'regular' annotation.
Merge pull request #620 from square/jw/annotations

Use the annotations directly for parameter handling.
Provide explicit error kind for disambiguation of underlying cause.