[FEATURE] Make autoloader namespace aware - Part 2

Add more tests to and move the namespace logic to
a more logical place.

Change-Id: I4907fdadfb04f27b74849ae6b42b52d55c6e8bd6
Resolves: #39158
Releses: 6.0
Reviewed-on: http://review.typo3.org/12971
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn