Add 'not null' constraint to Entry date column
Remove FillInDateTransition

This can no longer be tested because we have a 'not null' constraint on
the date column.
Add date to Entry factory
Remove Entry#date wrapper

We now have a 'not null' constraint on date so it will never be missing.
Set date instead of created_at in OhlifeImporter
Remove day checking in settings spec

We don't need to check this anymore because we're no longer doing time
zone conversions. An entry has a date and that's all folks.
Merge pull request #97 from codecation/add-constraints-to-date

Add not null constraint to Entry date column