Add the ability to track unique/returning visitors!

* Add a bit to the RP's localStorage that says whether the user has visited before. This avoids the need for a cookie and giving rum-diary.org the ability to fingerprint the user.
* Send a new field to rum-diary.org from include.js - 'returning'
* Store returning in the db for the hit.
* Add a new directory 'example', which is an ultra-basic RP.
* Add two new fields to reduce.js->mapReduce = 'unique' and 'returning' to give the number of unique visitors and the number of returning visitors.
Use promises in the db's connect function to clean up flow control
Prepare for multiple models.
Separate generic model functionality from page_view
Trying to add user and site models. Not quite there yet.