added heroes computed property to superheroes controller to allow heroes tab to show # of heroes

added new checker.js controller for checker template
  has computed properties to show diagnostics for hero info

changed superheroes/show.js to return ''' if discStyles or majorDiscStyle are not set

added route for checker to router.js

updated facebook_link, gplus_link, pnprofile_link, twitter_link to not show icon if no URL

added hero count to tabbed-menu.hbs

new template checker.hbs to display diagnostic info on heroes missing certain information