stock: Show the available number of units in the parenthesis

app/mailers/spree/stock_mailer.rb

@@ -45,7 +45,7 @@ module Spree
 	days = var.count_on_hand / mean
 
         {'weighted_mean' => mean, 'days' => days, 'variant' => var,
-            'product' => var.product, 'name' => name}
+            'product' => var.product, 'name' => name, 'available' => var.count_on_hand}
     end
 
     def generate_forecast()

app/views/spree/stock_mailer/stock_report_email.text.erb

@@ -5,7 +5,7 @@ will run low.
 
 Estimates:
 <% @forecast.each do |dict| %>
-<%= dict['name'] %> => <%= dict['days'].round(2) %> days until sold out.
+<%= dict['name'] %> (<%= dict['available'] %>) => <%= dict['days'].round(2) %> days until sold out.
 <% end %>