Disable login button

[Info 3bits]

Add an option to disable the login button in the top right corner.

This would be useful for sites that have a login block

[Alexander Goryntsev]

That's my case. So far I've made it with custom CSS:

 .btn-login {
     display: none;
 }

[Info 3bits]

Fixes #480

→ <<cset c6ffe229bc4c>>