Make curl follow redirections. wget already does.

BUG=chromium-os:10289
TEST=manual

Set up a local URL that redirects, try it out. For example:

  ./recovery.sh http://www/~scottz/recovery2.conf

should redirect to http://www.corp.google.com/~scottz/recovery2.conf

Change-Id: I0a60784f414d69b9e3371b9546666dcdc8978d25

Review URL: http://codereview.chromium.org/5818002

user_tools/linux/recovery.sh

@@ -191,10 +191,10 @@ fetch_url() {
     if [ -z "$resume" ]; then
       # quietly fetch a new copy each time
       rm -f "$filename"
-      curl -f -s -S -o "$filename" "$url"
+      curl -L -f -s -S -o "$filename" "$url"
     else
       # continue where we left off, if possible
-      curl -f -C - -o "$filename" "$url"
+      curl -L -f -C - -o "$filename" "$url"
       # If you give curl the '-C -' option but the file you want is already
       # complete and the server doesn't report the total size correctly, it
       # will report an error instead of just doing nothing. We'll try to work