AFOAuth1Client支持 OAuth 1.0a 认证的 AFNetworking 扩展

AFNetworking 的扩展，用于支持 OAuth 1.0a 认证。

示例代码：

AFOAuth1Client *twitterClient = [[[AFOAuth1Client alloc] initWithBaseURL:[NSURL URLWithString:@"https://twitter.com/oauth/"] key:@"..." secret:@"..."] autorelease];

// Your application will be sent to the background until the user authenticates, and then the app will be brought back using the callback URL
[twitterClient authorizeUsingOAuthWithRequestTokenPath:@"/request_token" userAuthorizationPath:@"/authorize" callbackURL:[NSURL URLWithString:@"x-com-YOUR-APP-SCHEME://success"] accessTokenPath:@"/access_token" success:^(AFOAuth1Token *accessToken) {
    NSLog(@"Success: %@", accessToken);
    NSLog(@"Your OAuth credentials are now set in the `Authorization` HTTP header");
} failure:^(NSError *error) {
    NSLog(@"Error: %@", error);
}];