store Visit in database instead of calculating them

next pageview WIP

two pending tests are waiting for a better coding day

rewrite next_pageview spec to integration spec, create generator for pageviews with events

timestamp stores time in miliseconds

require gems instead of specifying them in Gemfile

remove resort from dependencies

 move visit functionality to activerecord model

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

add subpage and link to it in dummy app

fix combining pageviews without any events

show next pageview path in current pageview data