moved all metadata.go function calls into method calls for the Halo
struct. This will make it easier to encapsulate baseurl, apikey, blah
blah, and also makes the code a little bit more readable. Stats.go and
profile.go are to follow.
Still need to implement http.Client interface and look over the code in
go-halo5-api.go. Most likely needs to break out and be cleaned up
