Enable https:// for 'image' in the Authentication Hash

[Matwolf08]

I have modified the code of the Facebook Strategy class to use https:// or http:// for the URL of the Facebook user image inside the Authentication hash.
I use a new boolean parameter (eg. :secure) passed on provider declaration:

provider :facebook, ENV['FACEBOOK_KEY'], ENV['FACEBOOK_SECRET'], :secure => true

The code of the Facebook Strategy class that I've changed is in this gist: https://gist.github.com/2014580

I hope that you can implement something similar for the next version of the gem, it's useful (IMHO) for websites that use SSL to avoid browser complaints about inclusion of unsafe resources! ;)