follow curl redirects

Update `curl` commands to follow redirects (see
http://curl.haxx.se/docs/manpage.html#-L). Current `curl` commands will
return unexpected results if the requested content has been moved and is
returning information about where it has been moved to. Including the
`-L` option tells `curl` to follow the redirect so the file can be
correctly acquired.
Merge pull request #7475 from bbodenmiller/curl-redirects

follow curl redirects