Use #teamops-friendly justification in CAP proposals

app/models/create_cap_proposal.rb

@@ -63,7 +63,9 @@ def link_to_product
   end
 
   def justification
-    "To procure software to support an 18F or 18F client project via the micro-purchase platform."
+    %{
+      Billable to the '#{@auction.billable_to}' Tock line item.
+    }
   end
 
   def cost_per_unit

app/models/presenter/auction.rb

@@ -13,6 +13,7 @@ def initialize(auction)
     end
 
     delegate(
+      :billable_to,
       :created_at,
       :delivery_deadline,
       :delivery_url,

spec/models/create_cap_proposal_spec.rb

@@ -31,5 +31,10 @@
       url = auction_presenter.winning_bid.bidder.credit_card_form_url
       expect(c2_proposal_hash[:additional_info]).to include(url)
     end
+
+    it 'includes the billable_to field in the justification' do
+      billable_to = auction.billable_to
+      expect(c2_proposal_hash[:justification]).to include(billable_to)
+    end
   end
 end