code: def config_content(self, command, vars):
          
          settable_vars = [
                  var('db_url', 'Database url for sqlite, postgres or mysql', 
                      default='sqlite:///%(here)s/studio.db'),
                  var('ms_url','Url to the mapserv CGI',
                      default='http://localhost/cgi-bin/mapserv'),
                  var('admin_password','Password for default admin user',
                      default=secret.secret_string(length=8))
          ]
  
          for svar in settable_vars:
              if command.interactive:
                  prompt = 'Enter %s' % svar.full_description()
                  response = command.challenge(prompt, svar.default, svar.should_echo)
                  vars[svar.name] = response
              else:
                  if not vars.has_key(svar.name):
                      vars[svar.name] = svar.default
  
          vars['cookie_secret'] = secret.secret_string()
  
          # call default pylons install
          return super(StudioInstaller, self).config_content(command, vars)
docs: Called by ``self.write_config``, this returns the text content
          for the config file, given the provided variables.