[test] Fix all places where test for definition() was wrong

This breaks a lot of tests:

68% tests passed, 7 tests failed out of 22
The following tests FAILED:
	  3 - DataArray (Failed)
	  5 - DataTag (Failed)
	  7 - Entity (Failed)
	 16 - Property (Failed)
	 17 - Section (Failed)
	 18 - SimpleTag (Failed)
	 19 - Source (Failed
NamedEntityHDF5::definition() only set optional if getAttr == T

Fixes the NamedEntityHDF5::definition part of issue #233
Merge pull request #242 from gicmo/issue_233_definition

Fix NamedEntity::definition to correctly return none
this time in the right order :-)