Publish a manifest.json

[tcarreira]

Relative to tsuru/tsuru-client#172

In order to support installing the rpaasv2 plugin using the tsuru-client, this project must publish a manifest.json
The example for version v0.33.1 would the following:

{
  "SchemaVersion": "1.0",
  "Metadata": {
    "Name": "rpaasv2",
    "Version": "0.33.1"
  },
  "UrlPerPlatform": {
    "darwin/amd64": "https://github.com/tsuru/rpaas-operator/releases/download/v0.33.1/rpaasv2_0.33.1_Darwin_x86_64.tar.gz",
    "darwin/arm64": "https://github.com/tsuru/rpaas-operator/releases/download/v0.33.1/rpaasv2_0.33.1_Darwin_arm64.tar.gz",
    "linux/amd64": "https://github.com/tsuru/rpaas-operator/releases/download/v0.33.1/rpaasv2_0.33.1_Linux_x86_64.tar.gz",
    "linux/arm64": "https://github.com/tsuru/rpaas-operator/releases/download/v0.33.1/rpaasv2_0.33.1_Linux_arm64.tar.gz",
    "linux/386": "https://github.com/tsuru/rpaas-operator/releases/download/v0.33.1/rpaasv2_0.33.1_Linux_i386.tar.gz",
    "windows/amd64": "https://github.com/tsuru/rpaas-operator/releases/download/v0.33.1/rpaasv2_0.33.1_Windows_x86_64.zip"
    "windows/386": "https://github.com/tsuru/rpaas-operator/releases/download/v0.33.1/rpaasv2_0.33.1_Windows_i386.zip",
  }
}