Feature: add tags to posts

[takanome-dev]

Currently, posts don't ave tags. It's a nice to have i think...

TODO

• add a new table tags in the db (if necessary)
• add tags to posts
• what else?

Question (for anyone)

Should you save a post's tags as a string and save each tag in a table for filtering or the post's tags should be ids (relationship with tags table)?