A view for admin tag page

new file:   views/admin/tags.jade
  view for the admin page to modify tags

modified:   app.js
  add the route for /logout

modified:   routes/tags.js
  change tes responce spec, every response message should fave type and
  content.

modified:   routes/tellusadmin.js
  add the route for /tellusadmin/tags. add a middleware isAuth to check
  if user had login.