Add Client::github constructor

examples/github.rs

@@ -0,0 +1,15 @@
+extern crate inth_oauth2;
+
+use inth_oauth2::Client;
+
+fn main() {
+    let client = Client::github(
+        "01774654cd9a6051e478",
+        "9f14d16d95d605e715ec1a9aecec220d2565fd5c",
+        Some("https://cmcenroe.me/oauth2-paste")
+    );
+
+    let auth_uri = client.auth_uri(Some("user"), None).unwrap();
+
+    println!("{}", auth_uri);
+}

src/lib.rs

@@ -47,6 +47,22 @@ impl Client {
         }
     }
 
+    /// Creates a GitHub OAuth 2.0 client.
+    pub fn github<S: Into<String>>(
+        client_id: S,
+        client_secret: S,
+        redirect_uri: Option<S>
+    ) -> Self {
+        Client {
+            auth_uri: String::from("https://github.com/login/oauth/authorize"),
+            token_uri: String::from("https://github.com/login/oauth/access_token"),
+
+            client_id: client_id.into(),
+            client_secret: client_secret.into(),
+            redirect_uri: redirect_uri.map(Into::<String>::into),
+        }
+    }
+
     /// Constructs an authorization request URI.
     pub fn auth_uri(&self, scope: Option<&str>, state: Option<&str>) -> ParseResult<String> {
         let mut uri = try!(Url::parse(&self.auth_uri));