Domain media info: ensure media_object is a dict
Approval checkmarks: initialize approval_time
Link hiding: don't hide own posts due to low score

Also refactored logic of this section to be a lot simpler.
jsontemplates.py: data_attrs cleanup

Switched to better multi-line format/indentation, fixed whitespace,
added trailing commas, and alphabetized all attr lists.
API: Add more subreddit attributes

Adds comment_score_hide_mins, public_traffic, submission_type,
submit_link_label, submit_text_label, type, user_is_banned,
user_is_contributor, user_is_moderator, user_is_subscriber
Cut subreddit stylesheet image reads over to new model.