Adding Haml html escaping.

Haml's HTML escaping option was not on, leaving the site open for xss
attacks. This would seem to fix it.

config/environment.rb

@@ -7,6 +7,7 @@
 # Load the rails application
 require File.expand_path('../application', __FILE__)
 Haml::Template.options[:format] = :html5
+Haml::Template.options[:escape_html] = true
 # Initialize the rails application
 Diaspora::Application.initialize!