Support if-none-match and if-match headers.

[cmrigney]

S3 and the Minio server both support conditional writes using If-None-Match and If-Match. Fwiw, this is already supported in the Go client.

Previously this was treating those parameters as metadata, but now they're treated as proper headers.

Example:

minioClient.putObject(
  "my-bucket",
  "my-object",
  "object-content",
  undefined,
  {
    "If-None-Match": "*",
  }
);

[prakashsvmx]

Thank you for the contribution @cmrigney . Could you please add a functional test ?

[harshavardhana]

Thank you for the contribution @cmrigney . Could you please add a functional test ?

@prakashsvmx lets take this and add functional tests ourselves.

[cmrigney]

Thanks! Sorry, I hadn't got around to it yet.