Display success and error message in the purchase subscription screen

[reyraa]

1. Users need a positive balance to purchase a subscription. Therefore we should display a summary of their account in the purchase subscription tab of the subscriptions page:
   • Address
   • Balance
2. Once they click on purchase, we should disable the button to prevent further interaction.
3. If an error occurs we should display the error message, and re-enable the purchase button.
4. If the action is successful, we should display a success command, and keep the purchase button disabled.