Work to do

For the Rails integration

Model

• Declare which model is "user" and which one is "instance"

model Member
   include Helioth::User
end

model Company
   include Helioth::Instance
end

• Link those models to the roles declared in the DSL (use rails Convention over configuration)

add_column :member, :helioth_roles, :string
add_column :instance, :helioth_roles, :string

• Let them respond to method like "is_roleName?" (ex: "is_beta?") etc.