Add single redirection support to picasso

We've been very happy using Picasso with our product.
One of our main usages is loading facebook friends profile pictures which unfortunately stopped working.

The reason was a redirection facebook added to the original profile image URL which prevented picasso from loading the images.(Since it doesn't follow redirections).

We've added support for the most basic use-case of a single redirection.

Please review and let us know if you have any comments.

Thank you,
Nati Dykstein.
Rounds Entertainment Inc.