Add option to disable invisible login and status via default.properties

Some companies may want to disable invisible login and status to force their users to be always visible. This can be added as an option to the default.properties file:
1. disable a checkbox on Login screen
2. remove invisible status from status selection

Although users will still be able to achieve the same effect setting up an appropriate privacy list, so this is a bit of security through obscurity type of feature, but still can be useful for some users.