Adds color attribute to conference

app/views/admin/conference/edit.html.haml

@@ -5,6 +5,7 @@
       = f.input :short_title, :hint => "A short title, such as 'osc2013', to be used in URLs"
       = f.input :social_tag, :hint => "The hashtag you'll use on Twitter and Google+.  Don't include the '#' sign!'"
       = f.input :contact_email, :hint => "Contact email address for your conference. Will be used as reply-to address in emails sent out by the system."
+      = f.input :color, :hint => "The color will be used eg for the dashboard.", :input_html => {:size => 6, :type => "color"}
 
       = f.inputs :name => "Scheduling" do
         = f.input :timezone, :as => :time_zone, :hint => "The conference time zone"