move login status constants into model

move the Login Status constants into Model
so they can be sued by the framework LoginScanner
classes
add NO_AUTH_REQUIRED

this status is needed for LoginScanner results
even thoguh it will never be used for a Login
add to the all group
Merge pull request #20 from rapid7/feature/MSP-10711/login-status

Feature/msp 10711/login status

MSP-10711 #land