- added information to several docblocks
- changed handling of request headers, added private property for this
- applied changes for improved use of require_once in the README and examples
- added `list_sites()` example
- *potential breaking changes:*
renamed `get_request_type()` and `set_request_type()` functions/methods to `get_request_method()` and `set_request_method()` respectively
- added a 6th parameter to the constructor to enable SSL cert verification, recommended for production environments
- added examples/change_wlan_password.php to demonstrate WLAN password/PSK change
- updated main README accordingly
