Replace the gear icon in the menu with a logout button

[foyarash]

In the menu, near the user informations, there currently is a gear icon which triggers a popup that allows the user to signout, and nothing much. This is kind of useless and it would be better to have a simple logout icon in place, removing the existing popup aswell.

[dikshita1920]

https://github.com/dikshita1920

[vincentwinkel]

In my case, I cannot insert a url to logout as the mecanism to logout is more complex. So indeed I put a link to the user profile. In this case I would have like to be able to change the icon. But it's a detail.