Updated the foreign exchange link to use configured currency.

app/helpers/application_helper.rb

@@ -17,7 +17,8 @@ module ApplicationHelper
 
   def forex_link(price)
     pid = price_in_dollars(price)
-    link = "http://www.wolframalpha.com/input/?i=#{pid}+aud"
+    currency = Growstuff::Application.config.currency
+    link = "http://www.wolframalpha.com/input/?i=#{pid}+#{currency}"
     return link_to "See exchange rates",
       link,
       :target => "_blank"

spec/views/shop/index_spec.rb

@@ -24,7 +24,8 @@ describe 'shop/index.html.haml', :type => "view" do
     end
 
     it 'should contain an exchange rate link' do
-      assert_select("a[href=http://www.wolframalpha.com/input/?i=9.99+aud]")
+      currency = Growstuff::Application.config.currency
+      assert_select("a[href=http://www.wolframalpha.com/input/?i=9.99+#{currency}]")
     end
 
     it 'shows recommended price for products that have it' do