Billing - Ability to charge clients directly

When creating invoices and subscriptions, you now have the ability to add a credit card on behalf of the client and charge the client directly.

Improvements and fixes

• Added logic that automatically adds your logo to invoices.
• Added a confirmation step when cancelling subscriptions.
• Redesigned the color picker on the Customization page to be more intuitive.
• Redesigned the invoice and subscription creation experience.
• Fixed a bug where on the client details page we showed payment-related information even if the billing section is disabled.
• Fixed a bug where clients who have not yet been invited still received some email notifications in rare circumstances.