2.0.0-beta2

• Added ProcessorConfig API for adding custom TypeAdapters and configuring other options in
  the processor.
• Deprecated RegisterAdapter API in favour of ProcessorConfig
• Deprecated PaperParcel.Options API in favour of ProcessorConfig
• Re-added Serializable support
• Performance improvements in the compiler and in the generated code
• Fix: allow use of "new" as a variable name in kotlin (as it isn't a kotlin keyword)
• Validate kapt version and give a helpful error message if the wrong version is being used
• Fix: allow use of contravariant generic types
• Greatly improve type matching system. This allows for adapters to handle complex generic types,
  including intersection types.