Assign a consistent value for "valid null" for events without dates

[mattstratton]

Events that do not have a date assigned will need their date set to TBD.

We will also need to trap for this in various places, which I'll figure out later.

This issue exists for historical documentation purposes only :)

[mattstratton]

Alternatively, we could have the sample datafile not set a value for these things at all.

I need to check to see if setting it as "nothing" will help with the isset.

[mattstratton]

This has been resolved. Events without a start date shoudl leave the value blank, not provide it as "TBD".