Remove all content-type headers as utf8 header is now supported by Asana
Remove all content-type headers as utf8 header is now supported by Asana

Asana fixed a bug in their API that didn't support the charset=utf-8 header.
This now works, so the standard Guzzle header from 3.4.2 onward for POST's
and PUT's now works and doesn't need an override.

arendjantetteroo/guzzle-asana