Do not specify default "Accept" header

Lines 132 to 134 in c7ba3e6

    
           if (!findHeaderName('Accept', init.headers)) { 
        
               init.headers.Accept = Client._jsonContentType; 
        
           }

There is no need to specify it. Because the server knows what content type to return. There is no ambiguity.

And since we specify json as the accept type, binary downloading stops working recently (due to a recent change on server side)

lines removed

	if (!findHeaderName('Accept', init.headers)) {
	init.headers.Accept = Client._jsonContentType;
	}