ENH: CMake vars in all caps. Optionally build VTK, CTK, etc using vars.

Signed-off-by: Stephen R. Aylward <stephen.aylward@kitware.com>
ENH: Qt/CTK is not built on most platforms
Merge pull request #3 from aylward/UseTubeTKUseVars

Use TubeTK_USE_XXXX variables to control dashboard configuration