Fixing rails 4.0.0beta, ruby 2.0 scopes bug

looks like mixing :conditions syntax in gem with where() syntax in my
model's association lambda munches association's scope, returning ALL
related_models!

so model.related_models.count == 1 but
model.related_models.unarchived.count == 14

upgraded scopes to rails 4 syntax (should also avoid warnings)... not
sure if there was a reason to keep the constants, so they're gone now