Restructure tables

[aubundy]

• [x] How to separate existing table?

• User Tags (user_id, tag_id)

• User Readings (user_id, reading_id)

• Reading Tags (reading_id, tag_id)

• Favorites

• Subscriptions

• Users

• Readings

• Tags

[aubundy]

return tag info in readings apicall normalize tag info into readings - each reading has tags key with array of tag ids tags - object key is tag id, value is array of tag_name, reading_id, user_id objects

    I'm returning tags id with readings now. 
    need to add user readings table - how to transfer data from one table to another?
        user id, reading id, created date
         IS READING_TAGS ALREADY THE USER READINGS TABLE I NEED?
            maybe a user tags table, user readings table, and reading tags table
                user -> tags, user -> readings, reading -> tags