Store location.time in seconds, not milliseconds

Resolves #7
New seed database, with changes to favorite table

 - Declare id column as INTEGER PRIMARY KEY, resolves #6
 - Add last_location column to track algorithm's progress, resolves #8
 - Also, check in the script used to create these tables
SQL script to migrate data (& add sample favorite)
Merge pull request #9 from coyotebush/db-cleanup

Miscellaneous database format cleanup