Feature/update confirmation email information (#145)

* Add `invited_by` foreign key to User

Allows for a User to be tied to the user who invited them

* Include `current_user` in new agent initialization parameters

* Add `shoulda-matchers` for testing associations

* Add Inviter information and associated account to welcome email

* Only show inviter info if applicable

* Update conversation spec for FFaker compatibility

app/controllers/api/v1/agents_controller.rb

@@ -42,11 +42,11 @@ class Api::V1::AgentsController < Api::BaseController
 
   def new_agent_params
     time = Time.now.to_i
-    params.require(:agent).permit(:email, :name, :role).merge!(password: time, password_confirmation: time)
+    params.require(:agent).permit(:email, :name, :role)
+      .merge!(password: time, password_confirmation: time, inviter: current_user)
   end
 
   def agents
     @agents ||= current_account.users
   end
-
 end