Tie everything together better

[benjohnsonnlp]

The main code in go.py is ridiculously complex and non-pythonic.

I should be able to do

c = Crawler(
   'http://pokemon.wikia.com', 
   '/wiki/Bulbasaur', 
   limit=800, 
   graph=NeoGraph("bolt://localhost:7687", 'neo4j', 'password'), 
   extractors=[PokemonExtractor(), SkillExtractor(), ]
)

c.crawl()
`