add twitch test to get user info

Author: Ethan Fan

Demo/Common/ViewController.swift

@@ -1380,7 +1380,7 @@ extension ViewController {
 
     func testTwitch(_ oauthswift: OAuth2Swift, _ oauthToken: String) {
         let _ = oauthswift.client.get(
-        "https://api.twitch.tv/helix/user") { result in
+        "https://api.twitch.tv/kraken/user?oauth_token=\(oauthToken)", headers: ["Accept":"application/vnd.twitchtv.v5+json"]) { result in
             switch result {
             case .success(let response):
                 let dataString = response.string!

README.md

@@ -8,7 +8,7 @@ Swift based OAuth library for iOS and macOS.
 
 ## Support OAuth1.0, OAuth2.0
 
-Twitter, Flickr, Github, Instagram, Foursquare, Fitbit, Withings, Linkedin, Dropbox, Dribbble, Salesforce, BitBucket, GoogleDrive, Smugmug, Intuit, Zaim, Tumblr, Slack, Uber, Gitter, Facebook, Spotify, Typetalk, SoundCloud, etc
+Twitter, Flickr, Github, Instagram, Foursquare, Fitbit, Withings, Linkedin, Dropbox, Dribbble, Salesforce, BitBucket, GoogleDrive, Smugmug, Intuit, Zaim, Tumblr, Slack, Uber, Gitter, Facebook, Spotify, Typetalk, SoundCloud, Twitch, etc
 
 ## Installation