deal with invites to existing users

ruby/lib/jam_ruby/app/mailers/invited_user_mailer.rb

@@ -40,6 +40,7 @@ module JamRuby
       @signup_url = generate_signup_url(invited_user)
       @sender = invited_user.sender
       @note = invited_user.note
+      @receiver = invited_user.receiver
       @suppress_user_has_account_footer = true
       sendgrid_category "Invitation"
       sendgrid_unique_args :type => "friend_invitation"

ruby/lib/jam_ruby/app/views/jam_ruby/invited_user_mailer/friend_invitation.html.erb

@@ -1,12 +1,24 @@
-<% provide(:title, "You've been invited to JamKazam by #{@sender.name}!") %>
+<% provide(:title, @receiver ? "#{@sender.name} would like you to be their friend on JamKazam" : "You've been invited to JamKazam by #{@sender.name}!") %>
 <% provide(:photo_url, @sender.resolved_photo_url) %>
 
-To signup, please go to the <a style="color: #ffcc00;" href="<%= @signup_url %>">create account</a> page.
+<% if @receiver %>
+<a style="color: #ffcc00;" href="<%= @signup_url %>">Click here</a> to accept.
 
 <% content_for :note do %>
-    <% if @note %>
-        <%= @sender.name %> says: <%= @note %>
-    <% else %>
-        <%= @sender.name %> would like you to join JamKazam.
-    <% end %>
+<% if @note %>
+<%= @sender.name %> says: <%= @note %>
+<% else %>
+<%= @sender.name %> would like you to be their friend on JamKazam, so that you can play in private sessions together.
+<% end %>
+<% end %>
+
+<% else %>
+To signup, please go to the <a style="color: #ffcc00;" href="<%= @signup_url %>">create account</a> page.
+<% content_for :note do %>
+<% if @note %>
+<%= @sender.name %> says: <%= @note %>
+<% else %>
+<%= @sender.name %> would like you to join JamKazam.
+<% end %>
+<% end %>
 <% end %>