Adding the ability to replace the default background image and improvements to the logout scheme

[luizjr]

I felt like I would like to customize the image without having to generate a new image or having to create a repository, host my docker image, and I would only need to set one more variable!

[luizjr]

Add return page to redirect the user after successful logout

I'm suggesting using the same configuration we used for login when redirecting to the service, we are pointing back to the login that will send to the service again and not to another's login page without sending to the service we want.

We can also call a route directly from the service and log out of another ldap

[luizjr]

@dignajar This pull will be implemented?

[dignajar]

I need to check that redirect you add; For sure the image from outside is not the way I prefer to keep it as a static file.. I will try to do some workaround.

[luizjr]

I need to check that redirect you add; For sure the image from outside is not the way I prefer to keep it as a static file.. I will try to do some workaround.

The still image continues! You will only be able to add another one if you want.

As for the redirection, it's actually good for you to test it too! But the intention is to implement Logout