profile: locks login fields if disable_login_form

If the auth config variable, disable_login_form, is set to true then
the username and email fields are set to read-only on the profile page.

The reason for this is so that the user does not lock themselves out by
changing their email address or username. Or create a new user by
changing both.

ref #7810

public/sass/_grafana.scss

@@ -85,6 +85,5 @@
 @import "pages/signup";
 @import "pages/styleguide";
 
-
 @import "old_responsive";
 @import "components/view_states.scss";