The DateTimeToLocalizedStringTransformer when used with a pattern that have only date (in DateType for instance) does not convert the result in the desired output

Reproduction steps:

• Use DateType in a form
• Set the model_timezone to Pacific/Tahiti, having default timezone to Europe/Berlin.
• Enter the date 2017-01-10
• Submit the form
• Notice that the received data is 2017-01-10 00:00 Europe/Berlin, whereas it should be 2017-01-10 11:00 Europe/Berlin

Incoming pull request with tests and proposed resolution.

(ping @tsurenas for finding it)