Made changes to use new data structure - flat voyage layout

all voyages are now flattened out. Used to be that all the voyages were
listed under a ship.
{
	"_id" : ObjectId("530d229c421aa92ca59e14dd"),
	"voyage" : "046N",
	"scrape_date" : ISODate("2014-02-25T18:09:16.338Z"),
	"url" : "http://www.shipmentlink.com/tvs2/download_txt/NEAX_N.html",
	"carrier" : "Evergreen",
	"vessel" : "ASTORIA BRIDGE",
	"ports" : [
		{
			"port_info" : {
				"latitude" : -37.8175,
				"port_code" : "AUMEL",
				"city_code" : "MEL",
				"longitude" : 144.967,
				"country_code" : "AU"
			},
			"eta" : ISODate("2014-03-18T00:00:00Z"),
			"port" : "MELBOURNE",
			"etd" : ISODate("2014-03-20T00:00:00Z")
		}….
}