Merge pull request #11 from plesf/bug/no_checkins

Revised User.get_last_checkin() to handle case where user does not have ...
Added the first cut of the scheduled tasks script, this is just a rough version, does not currently work
Update README.rst

Added the db_create instruction to the readme
Added a phone number field for the signup form, as well as a validation function and a column for the db
Modified the get_last_checkin function to only return a checkin if it is a new checkin
Got the first cut of the scheduled tasks script up and running