Use username instead of email in Devise mails

app/views/devise/mailer/confirmation_instructions.html.erb

@@ -1,5 +1,5 @@
-<p>Welcome <%= @email %>!</p>
+<p>Welcome <%= @resource.cn %>!</p>
 
-<p>You can confirm your account email through the link below:</p>
+<p>Please confirm your email address through the link below:</p>
 
 <p><%= link_to 'Confirm my account', confirmation_url(@resource, confirmation_token: @token) %></p>

app/views/devise/mailer/email_changed.html.erb

@@ -1,4 +1,4 @@
-<p>Hello <%= @email %>!</p>
+<p>Hello <%= @resource.cn %>!</p>
 
 <% if @resource.try(:unconfirmed_email?) %>
   <p>We're contacting you to notify you that your email is being changed to <%= @resource.unconfirmed_email %>.</p>

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

@@ -1,3 +1,3 @@
-<p>Hello <%= @resource.email %>!</p>
+<p>Hello <%= @resource.cn %>!</p>
 
 <p>We're contacting you to notify you that your password has been changed.</p>

app/views/devise/mailer/reset_password_instructions.html.erb

@@ -1,4 +1,4 @@
-<p>Hello <%= @resource.email %>!</p>
+<p>Hello <%= @resource.cn %>!</p>
 
 <p>Someone has requested a link to change your password. You can do this through the link below.</p>
 

app/views/devise/mailer/unlock_instructions.html.erb

@@ -1,4 +1,4 @@
-<p>Hello <%= @resource.email %>!</p>
+<p>Hello <%= @resource.cn %>!</p>
 
 <p>Your account has been locked due to an excessive number of unsuccessful sign in attempts.</p>