Add "mystery man" gravatar to options (#7640).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@5109 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/views/settings/_display.rhtml

@@ -15,7 +15,7 @@
 
 <p><%= setting_check_box :gravatar_enabled %></p>
 
-<p><%= setting_select :gravatar_default, [["Wavatars", 'wavatar'], ["Identicons", 'identicon'], ["Monster ids", 'monsterid'], ["Retro", "retro"]], :blank => :label_none %></p>
+<p><%= setting_select :gravatar_default, [["Wavatars", 'wavatar'], ["Identicons", 'identicon'], ["Monster ids", 'monsterid'], ["Retro", 'retro'], ["Mystery man", 'mm']], :blank => :label_none %></p>
 </div>
 
 <%= submit_tag l(:button_save) %>