Fixed issue#468 - ”Password has been changed" email contains unresolved placeholders.

app/views/mailer/password_change/en.html.erb

@@ -1,9 +1,9 @@
-Your #{product_name} password has been changed
+Your #{config.product_name} password has been changed
 
 <p>Hi #{user.firstname},</p>
 <br>
-<p>The password for your #{product_name} account <b>#{user.login}</b> has been changed recently.</p>
+<p>The password for your #{config.product_name} account <b>#{user.login}</b> has been changed recently.</p>
 <br>
 <p>This activity is not known to you? If not, contact your system administrator.</p>
 <br>
-<p>Your #{product_name} Team</p>
+<p>Your #{config.product_name} Team</p>