Updated addSignatureHeader to set url for custom sites without ports
Updated addSignatureHeader to set url for custom sites without ports

ionux/php-bitpay-client,bitpay/php-bitpay-client,initaldk/php-bitpay-client,samuelbohler/php-bitpay-client,bitpay/php-bitpay-client,eXcomm/php-bitpay-client,samuelbohler/php-bitpay-client,eXcomm/php-bitpay-client,initaldk/php-bitpay-client,ionux/php-bitpay-client