Remove display of Novalnet-Logo to customers

Hi!

I really think, the Novalnet-Logo should not be displayed face to the customer, because of three reasons

1. Many customers don't know what "Novalnet" is. They'll have to check upon Novalnet and/or will call the store -> More work, because we have to deal with the customers.
2. Novalnet can also be used in background without being disclosed by payment-forms (when using the non-pci-forms). In that case, the customer should not be informed, that Novalnet is processing the payment
3. The linked logo is really big and can crash the site-layout. Aditionally, it has no classes, so it cannot be influenced by CSS.

Attached you find a patch that removes the display of the Novalnet-Logo.

If you do not want to incorporate this patch for any reason, please think about putting the Logo-Link also inside the t(), so the user can remove the logo himself by using the translation-tools. Or add a switch, that en- or disables the display of the logo.