http client: option to not raise errors

Pass raise_error=False to the fetch method to disable the raising of
HTTPError on errors.
use the same protocol when redirecting to default host
Merge pull request #1260 from lilydjwg/no-handler-redirect

use the same protocol when redirecting to default host
swap platform.system() for sys.platform; #1263
Merge pull request #1264 from nbargnesi/master

swap platform.system() for sys.platform
Merge pull request #1258 from tdyas/no_raise_error

http client: option to not raise errors