Adding datetime support

* Removed support for specifying the namespace as an array in preference of the the `:namespace` option.
* Added `datetime_parser` controller method for parsing date and time input fields to a DateTimeobject.
* Added travis support
* Removed the need to include DateParams::ControllerAdditions into the controller
* Assume the datetime field is composed of a field_date and field_time set of fields
Merge pull request #1 from LessonPlanet/jr/add-datetime-support

Adding datetime support