GetSecurityBanner invalid user error

[rwakida]

To replicate:

1. Create a channel
2. Select "general" channel
3. logout.

[method]getSecurityBanner invalid user error should briefly appear in upper right

[rwakida]

After investigation, the getSecurityBanner method was reactively called after the user logged out. Thus the serverside method threw an error because no userId existed. I modified the getSecurityBanner method to not check for userId because it doesn't return/access sensitive information and doesn't require a user.