* core/templates/base.html:
    - Added analytics tracking code.
 * core/models.py && core/templates/core/post_detail.html && core/templates/core/post_list.html
    - Added caching of content.
    - Added flush of cache on save.
    - Added check if we are adding new entry in Post before sending
mails. There was annoying issue of resending mails on edit of Post.