Support for Flickr https endpoints

Flickr has stopped allowing access via http, and now requires applications to use https. This change switches the FlickrApi and FlickrExample classes to use the new https endpoints.

In addition, a line of output was added to the FlickrExample class to show where the Flickr username data that is sent back with the token can be found.

I have tested the example successfully with my own Flickr API key and secret.