API client class v1.1.63
- 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