Include first/last name in invitation emails

app/views/notifier/invite.markerb

-<%= t('.message', :invite_url => invite_code_url(@invitation_code), :diasporafoundation_url => 'https://diasporafoundation.org/', :diaspora_id => @inviter.try(:diaspora_handle)) %>
+<%= t('.message',
+  invite_url: invite_code_url(@invitation_code),
+  diasporafoundation_url: 'https://diasporafoundation.org/',
+  user: @inviter.try(:diaspora_handle) == @inviter.try(:name) ?
+    @inviter.try(:diaspora_handle) :
+    @inviter.try(:name) + " (" + @inviter.try(:diaspora_handle) + ")",
+  diaspora_id: @inviter.try(:diaspora_handle))
+%>

config/locales/diaspora/en.yml

@@ -807,7 +807,7 @@ en:
       message: |-
         Hello!
 
-        You have been invited to join diaspora* by %{diaspora_id}!
+        You have been invited to join diaspora* by %{user}!
 
         Click this link to get started