Update security "paths" to use routes in 2.1

[weaverryan]

From @vicb - for example: http://symfony.com/doc/master/book/security.html#using-a-traditional-login-form

In Symfony 2.1, using routes - instead of hard-coded paths, is preferred. We should update this, and find any other instances of this in the docs.

[wouterj]

I will do this, but which routes do you mean? Do you mean the routes for the firewall or the login form?

[stof]

the login path, the login check path and the logout path

[wouterj]

@stof thank you.