add customization to the login page

[thomasbeaudry]

Content

Currently, there is no place to customize your ODC login page. It would be good to be able to add a name for the instance, a description, and possibly a picture and logo (less important). This would be good to have if you have several instances (we have 1 for humans and 1 for mice).

Also, if somone discovers an odc instance (though google for instance), it's good to know what this page is. There is also no links to odc github or docs on the bottom of the login page. This is good for product discovery.