Adding autodj_threshold, autodj_timer, enforcement

Added user options to change the following:
- enforcement (defaults to 'on')
    - This works with 'set_limit', but you can now toggle 'enforcement' without changing the song limit DJ's have.

- autodj_threshold (defaults to 2 open spots, only used if autodj: true)
    - This allows users to set the number of open spots at which the bot should be allowed to autodj. ex: set to '4' so he'll DJ if there's only 1 DJ. He'll detect if the threshold is met, and automatically jump down to make space if he's not DJing, or wait until after his song if he's playing one. 

- autodj_timer (defaults to 60 seconds)
    - Set to your preference. I like 10 seconds personally, so if there's only 1 DJ he'll jump up in time to not interrupt the song playing for the current DJ who's all alone.

You should add these to your mybot.js and customize them to your liking, but they all have defaults in index.js if you don't.

    autodj_threshold: 2, // Number of open DJ spots needed for the bot to Auto DJ, if 
    autodj_timer: 60, // Number of seconds to wait for autodj
    enforcement: 'on', // Set enforcement 'on' or 'off'. If it's on, it'll use set_limit for max songs. If 'off', it'll ignore set_limit