Overall Structure for classes and API

[jeffreyliu]

Recipe proposed structure

classdef Recipe(url):

def run():
    context.getMeta(url) # gets metadata from context service
    payload = recipe.harvest()
    try:
        archiveDB.upload(payload) #upload call also runs validation tests
    except validationError:
        # User needs to fix the recipe so that it passes the tests

def harvest():
    # main function, must return a payload and associated metadata