Authenticate to Google Analytics

See doc/ingest-analytics.md for notes
Fairly dumb JSON pager for GA results

Google Analytics JSON pager - works like an enumerable returning 3
-column arrays containing hostname, path and pageviews.
Add Hit importing for GA-style rows

We don't have a GA account (yet). We're importing from array rows
consisting of [host, path, pageviews] until we do (as that's what
Transition::Google::ResultsPager returns)
Be explicit about what constitutes Hit::Never