Reduce download_url() timeout value

Timeout of 30 is too high. I've seen first hand a Bluehost shared hosting site timing out in the wp-admin Widgets page under the load of about 20 image widgets. I'm sure there are worse hosts out there and other cases of even higher image widget usage.

It seems better to err lower since it looks like the remote fetch is just used to optimize rendering layout. The widget looks like it works fine even if you comment download_url() out entirely.