Added an option to turn user Gravatars on or off

* Option can be found in Administration > General, called
  "Use Gravatar user icons"
* Defaulting Gravatars to off
* Added a helper gravatar_for_mail to check the setting before rendering
  the Gravatar.

  #1776


git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@1972 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/views/account/show.rhtml

@@ -2,7 +2,7 @@
 <%= link_to(l(:button_edit), {:controller => 'users', :action => 'edit', :id => @user}, :class => 'icon icon-edit') if User.current.admin? %>
 </div>
 
-<h2><%= gravatar @user.mail unless @user.mail.empty? %> <%=h @user.name %></h2>
+<h2><%= gravatar_for_mail @user.mail unless @user.mail.empty? %> <%=h @user.name %></h2>
 
 <p>
 <%= mail_to(h(@user.mail)) unless @user.pref.hide_mail %>
@@ -29,4 +29,4 @@
 <h3><%=l(:label_activity)%></h3>
 <p>
 <%=l(:label_reported_issues)%>: <%= Issue.count(:conditions => ["author_id=?", @user.id]) %>
-</p>
+</p>