ENH: Avoid adding invalid path to the sys.path
ENH: Avoid adding invalid path to the sys.path

The hard coded relative path was incorrect for the lib
directory.

Improved the variable names, and add checking for
the existence of the required Configuration subdirectory
for every itkConfig.path element.  Provide failure
diagnostics with useful message.

richardbeare/ITK,LucasGandel/ITK,BRAINSia/ITK,richardbeare/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,LucasGandel/ITK,hjmjohnson/ITK,vfonov/ITK,hjmjohnson/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,BRAINSia/ITK,vfonov/ITK,thewtex/ITK,richardbeare/ITK,thewtex/ITK,BRAINSia/ITK,thewtex/ITK,BRAINSia/ITK,hjmjohnson/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,Kitware/ITK,vfonov/ITK,richardbeare/ITK,richardbeare/ITK,hjmjohnson/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,LucasGandel/ITK,vfonov/ITK,thewtex/ITK,hjmjohnson/ITK,LucasGandel/ITK,Kitware/ITK,LucasGandel/ITK,LucasGandel/ITK,LucasGandel/ITK,vfonov/ITK,Kitware/ITK,LucasGandel/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,richardbeare/ITK,hjmjohnson/ITK,vfonov/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,BRAINSia/ITK,BRAINSia/ITK,thewtex/ITK,Kitware/ITK,richardbeare/ITK,Kitware/ITK,BRAINSia/ITK