• changed references to UbiOS back to UniFi OS
• removed capitalization from all header strings (per RFC, header fields are case-insensitive: https://tools.ietf.org/html/rfc7230#section-3.2)
• removed charset parameter from headers (not required per RFC)
• added x-csrf-token header to all requests except GET when talking to UniFi OS-based controllers, thanks go to @paciks for raising #86