Datetimes aren't properly formatted when inserting new data

[mattbdean]

Steps to reproduce:

1. Load any form with a datetime or timestamp column
2. Fill out that form and submit

Here's the error message:

"datetime" must be a string with one of the following formats [YYYY-MM-DD HH:mm:ss]

The value of the datetime input is "2017-01-01 12:00"