Adjust to reactive-commons library according to the CloudEvents specification.

[adsanta]

Hello everyone,

We found the need for the reactive-commons library to be adjusted so that there is the possibility of listening and emit events and commands with a structure aligned to the CloudEvent specification, as seen in the following structure:

{
    "specversion" : "1.0",
    "type" : "com.github.pull_request.opened",
    "source" : "https://github.com/cloudevents/spec/pull",
    "id" : "A234-1234-1234",

    "time" : "2018-04-05T17:31:00Z",
    "subject" : "123",
    "datacontenttype" : "application/json",
    "data" : { ... },

    "comexampleextension1" : "value",
    "comexampleothervalue" : 5
}

It should be noted that the key comexampleextension1 and comexampleothervalue can be any additional extension context attribute with any name that is needed for each use case, so as many extension context attributes can be included as required, according to the official specification of CloudEvents .

[juancgalvis]

@adsanta @jcanacon thank you by your contribution.

This issue has been closed by #115 and will be available initially at 5.0.0-alpha version