WIP
change associations with visit and visitor WIP
CreatePageview service WIP, set pending tests
add pageview to visitor in CreatePageview
Visitor#add_pageview
create_with_pageview accepts only pageview as argument
Visit#combine! method
Visit.create_with_pageview
pass an instance of Pageview in add_pageview test
fix return values for add_pageview
Pageview#next_pageview method
fabricate pageview without events when it's not necessary
update visitors controller spec
update visitor spec - remove PageviewCombiner from test
update events api spec
CreateEvent class
remove timestamp method from visti
remove unused last_event method from visitor
remove visit collection