Revert "Ensure TimeAxis w/o orientation fails cleanly"

This reverts commit ecda6ffe1aea6d3ec98d81d4f0e10776992d2395.
Ensure TimeAxis w/o orientation fails cleanly
  Fix minor bug where if TimeAxis is instantiated w/o an orientation, it fails
  in a hard-to-decipher way because the orientation.toLowerCase() breaks on
  input before the AbstractAxis class has a chance to throw a proper error.