2.0.0-rc2

This release biggest —and possibly breaking— changes are:

• Schema Object is now a superset of JSON Schema Draft 07: https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#schemaObject.
• Rename protocolInfo to bindings.
• Add bindings to Server Object: https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#serverObject.
• Restricts most common protocols in the Bindings Object.
• Fixes Security Requirement Object definition.
• Add parameter location: https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#parameterObject.
• Add missing security scheme types (they were on the JSON Schema definition but not on the Markdown one).
• Now parameters is an object/map instead of an array: https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#parametersObject.
• Now servers is an object/map instead of an array: https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#serversObject.
• Remove variables support from traits and simplifies syntax: https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#messageTraitObject and https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#operationTraitObject.
• Remove baseChannel from the Server Object.
• Remove support for non-JSON schemas, like Protobuf and XSD.
• Message headers are a JSON Schema object again: https://github.com/asyncapi/asyncapi/blob/2.0.0-rc2/versions/next/asyncapi.md#messageObject.
• Id is now optional.