Add color, description columns, and make type NOT NULL.
Add api handling and tests for color and description fields
Add -n to automatically generate tag slugs if they already exist
Merge branch 'api-tags-14' into migration-script
Save category color and description into tags
Cleaner handling of category parents during import

* Import from API using 2 passes: 1st parents, 2nd children
* Store IDs in tag_map not slugs.
* Auto generate slugs, don't use hack with old id in slug.
Fix error in SQL import using wrong variable name