ctkBackTrace: bug fix discovered on MacOSX, the method signature was wrong
adding the assessor, assessor folder and assessor resource classes
adding the XSI schema types for assessors
removing unused includes
adding assessors in the cmakelists
adding the assessor related methods in the session class
adding the assessor related methods in the session class
adding some debug information, temporary
The Assessor support is working properly, including the download function
removing unused qdebugs
removing unused qdebugs
CRASH-FIX: When the http request fails, a ctkException is thrown and never catched at the ctkXnat* level, making the whole application to crash, we need to try-catch every instance of the method httpResults(), it is done here at the Experiment level
FEATURE-ADD: adding all the xnat properties in the description of the ctkXnatObject so that they appear as tooltip in the tree.
Merge remote-tracking branch 'ntoussaint/CTK-XNAT-Library-AssessmentObject' into xnat-assessment-support

Conflicts:
	Libs/XNAT/Core/ctkXnatDefaultSchemaTypes.cpp
	Libs/XNAT/Core/ctkXnatDefaultSchemaTypes.h
	Libs/XNAT/Core/ctkXnatExperiment.cpp
	Libs/XNAT/Core/ctkXnatSession.cpp