Remove $table->dateTime() and correct $table->date()

Remove $table->dateTime() and modify $table->date() to reflect its creation of a DATETIME equivalent.

$table->dateTime() doesn't exist in laravel 4, yet the source reveals that date() returns a DATETIME equivalent. Is datetime() to be added? What about fields that require a DATE equivalent?

For now, this change correctly reflects behaviour of laravel 4.0