Added functionality to add new Categories
Added template to add new Categories
Added function to display all Categories
Added template to display all Categories
Added CategoryToPost model
Added categories to posts
Updated templates to use categories
Updated models names, added a many to many model (PostTags) to store the
reference key of a specific post and a list of tags associated with that
post
Search and replaced category with tags, categories with post_tags,
CategoryToPost with PostTags
Updated docstrings and comments, added functionality to add/update
post tags when editing a post
Updated base template
Updated the index template to display the post tags
Updated the newpost, viewpost and editpost templates to display post tags
Deleted old templates
Updated the field 'created' to have the attribute 'auto_now_add' which
will only set the current time the first time the model instance is stored
in the datastore.

This will allow users to edit/save posts afterwards without
changing/updating the 'created' date.
Added functionality to remove duplicates in list_tags before
updating/saving the post tags.
Updated template to truncate posts at 350 characters, updated template
comments.
Merge pull request #6 from p3dr0migue1/feature/add-tags

Added functionality to add, edit, and remove tags