mv_machine_learning: update face recognition framework

mv_machine_learning: update face recognition framework

[Version] : 0.23.10
[Issue type] : code updating

Updated face recognition framework and its test case including cleanup
and bug fix.

What this patch does,
	 - fix a bug that last label isn't removed by making all relevant files
	   to be removed when last label removal is requested.
	 - change default face recognition resource directory.
	 - add two test cases and code cleanup to existing test cases.

Change-Id: I8e172e03d8c0f355da1cd61b4a2567086c232813
Signed-off-by: Inki Dae <inki.dae@samsung.com>