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. For example:

https://raw.github.com/gitlabhq/gitlab-recipes/4-1-stable/init.d/gitlab

Now redirects to:

https://raw.githubusercontent.com/gitlabhq/gitlab-recipes/4-1-stable/init.d/gitlab