[x] In renaming "shows" "podcasts" I went a little overkill on the find + replace -- accidentally changed all the view files "show.json" to "podcast.json", so I've named those back to show to match their controller action.
[x] Changed invalid POST request to return 400 instead of 422 to match our other APIs #51
[x] Un-nested models under API (and re-nested Creative Controller, which snuck out of the api folder) #50
"show.json"to"podcast.json", so I've named those back to show to match their controller action.