Remove urchin protocol.
Remove obsolete PageViewActivity.
Remove PageViewActivity tests.
Remove obsolete Visitor.FirstVisitAt
Remove obsolete Session.HitId
Remove obsolete Session.HitCount
Remove obsolete Session.PreviousStartedAt
Remove obsolete Session.Number
Remove obsolete Session.StartedAt
Remove obsolete Session.
Minor clean-up.
Merge remote-tracking branch 'origin/master' into remove-urchin
Merge pull request #10 from AttackPattern/remove-urchin

Remove urchin protocol support from master in preparation for official 1.0 release.