Store dates in Unix time.

Dates can be stored in several formats. Unix time is being chosen because it seems to be the most convenient format to use (from my point of view, especially since I deal with Unix timestamps at work). It can always change in the future if one of the other options ends up being more convenient.
Create tables in the 'new' database.

The database created with the 'new' command now has tables created for it that match those defined in the design document. No initial data (such as a fingerprint) is inserted yet.
Added field for repository creation time.

A 'ctime' field exists for the main table 'hog' so that we will know when the repository was first created.