Add Sigmoid Analytics Adapter files to Legacy branch

[sigmoidanalytics]

Type of change

• [x ] Feature
• [x ] New analytics bidder adapter

Description of change

Adding the sigmoid analytics adapter files to legacy branch

• test parameters

{
  provider: 'sigmoid',
    options : {
      publisherIds: ["3gxdf18d32"]
    }
}

• contact email of the adapter’s maintainer
  ramees@sigmoidanalytics.com
• [ x] official adapter submission

[sigmoidanalytics]

@jaiminpanchal27 What do we need to do to list our analytics adapter here?
http://prebid.org/download.html
Our client can't work with advanced building, they can only download the packaged Prebid.js file by selecting required adapters from the download page. We need to make our adapter available in that page.

[jaiminpanchal27]

@sigmoidanalytics It takes around a week for download page to be updated. Once it is updated you will see the adapter.
https://github.com/prebid/Prebid.js/blob/master/RELEASE_SCHEDULE.md

[sigmoidanalytics]

@jaiminpanchal27 We are still unable to see the adapter in the analytics section in the download page.
http://prebid.org/download.html
The page is supposed to be updated every week?. Anything we are missing here?