Add UserAgent to the Request

[KevinJump]

To aid with some firewall / policy restrictions a user agent string should be sent with requests.

this might be a breaking change for existing installations, so will be opt in if implemented in v10.

[KevinJump]

Will be in v10.1

1. You can set the user agent string in config :
2. You can add your own custom header key pairs that will also get added to every request.

"uSync": {
    "Publisher": {
      "Settings": {
        "UserAgentString": "uSyncPublisherCustomString",
        "RequestHeaders": {
          "One": "ValueOne",
          "Two": "ValueTwo"
        }
   }
}