Changes in the Payment Card Form

[Iza-H]

Changes added to the code:

• Added an email parameter to the paymentRequestWithCardForm to can fill the form with a default value.
• added a currencySymbol to the paymentRequestWithCardForm to can personalize the Pay button in the form and to can change '$' to some other value.
• showing in the Pay button in the form amount in the float format with two decimal places.
  Regards

[lrettig]

Thanks for the PR, sorry I haven't had a chance to take a look yet, will merge asap!