Retrieving list of Subreddit emojis

[EliteMasterEric]

The Subreddit model should include functions to access the emoji endpoints:

https://www.reddit.com/dev/api/#section_emoji

Users with the read scope should be able to access the list of emojis available on a given subreddit, and users with the structuredstyles scopes should be able to upload and delete emojis.