Logout button

[danielo515]

There is a logout button, but it is only accessible while you are logging in, once you close the login form, there is no way to open it again.
This is because we use the same "sync" icon that Tyddlypouch does, and tiddlypouch does not have a modal for logging in.
The simplest solution will be to make the sync icon to open the login modal, which contains the logout button. However this will not look pretty, and I think a dedicated popup is required.
Such popup could contain the logout button and some extra fields like a checkbox to delete all the local databases as suggested on #49