'**SUMMARY**
Uploads all the images to imgur or flickr or dropbox. In verbose mode URL values are printed.
**PARAMETERS**
* *api_key* - a string of the API key.
* *api_secret* - (required only for flickr and dropbox ) a string of the API secret.
* *verbose* - If verbose is true all values are printed to the screen
**RETURNS**
if uploading is successful
- Imgur return the original image URL on success and None if it fails.
- Flick returns True on success, else returns False.
- dropbox returns True on success.
**EXAMPLE**
TO upload image to imgur::
>>> imgset = ImageSet("/home/user/Desktop")
>>> result = imgset.upload( \'imgur\',"MY_API_KEY1234567890" )
>>> print "Uploaded To: " + result[0]
To upload image to flickr::
>>> imgset.upload(\'flickr\',\'api_key\',\'api_secret\')
>>> imgset.upload(\'flickr\') #Once the api keys and secret keys are cached.
To upload image to dropbox::
>>> imgset.upload(\'dropbox\',\'api_key\',\'api_secret\')
>>> imgset.upload(\'dropbox\') #Once the api keys and secret keys are cached.
**NOTES**
.. Warning::
This method requires two packages to be installed
-PyCurl
-flickr api.
-dropbox
.. Warning::
You must supply your own API key.
Find more about API keys:
- http://imgur.com/register/api_anon
- http://www.flickr.com/services/api/misc.api_keys.html
- https://www.dropbox.com/developers/start/setup#python'

def upload(self, dest, api_key=None, api_secret=None, verbose=True):

    try:
        for i in self:
            i.upload(dest, api_key, api_secret, verbose)
        return True
    except:
        return False
