Support yaml uploads

[jackellenberger]

Resolves #9

Sometimes emoji live in yaml files. that's cool. we can support those.

We're expecting yamls to look like:

--- 
any_ignored_key: whatever
emojis:
  - name: emoji1
     src: emoji-src.jpg
  - name: emoji2
     is_alias: 1
     alias_for: emoji1

Either src or url can be used for the source image.

This also fixes the bug that i made by uhhhhh breaking upload somewhere down the line when called directly via cli. i should probably integration test the cli too. ugh.

Lastly, there was a weird thing where uploads were disappearing because superagentTrhottle was just eating my requests whole. very unclear why that was happening, but i've disabled superagentThrottle on emoji src retrieval for now. let me know if you get rate limited...