update to work with the changed flickr api

Changed the way the flickapi is called, to include the secret key and username, which appear to be required, in FlickrAPI:

class FlickrAPI(object): 
    REST_URL = 'https://api.flickr.com/servicesrest/'
    UPLOAD_URL = 'https://up.flickr.com/services/upload/'
    REPLACE_URL = 'https://up.flickr.com/services/replace/'
                                                                                                                                                                                                             
    def __init__(self, api_key, secret, username=None,
            token=None, format='etree', store_token=True,
            cache=False):                   

Everything except for api_key and secret have a default.  The original was only calling with "api_key" filled in, but bailing.  I also update ed the test to use my username, and now that passes.