Headers are encoded in iso-8859-1 per http rfc
Encode headers to iso-8859-1 when giving them to pycurl as well
Encode request method and url, as early pycurl versions do not accept unicode strings
On python 3, pycurl writes bodies to bytesios
Merge pull request #15 from p-push/pycurl-header-decoding

Unbreak header decoding/encoding on pycurl, including under python 3