ENH: Do not mark TubeTK_USE_KWSTYLE as advanced.

Improve visibility.

Change-Id: Ibf73f89bdb0606b97079a2878f1fa9c37644c450
STYLE: Fix KWStyle errors.

Change-Id: I5fdd2b1759a23c773fa6ac13b674fa19d47232e4
ENH: Use virtualenv for Base/ and Applications/ Python tests.

The tubetk Python module is installed into the Python testing virtualenv with
a .pth file and the virtualenv is used for the Base/ and Applications/ Python
tests.  No modifications to the local system are required anymore to test the tubetk
python package.
Merge pull request #84 from thewtex/KWStyleAdvanced

Kw style advanced
FIX: Virtual environment setup
Merge pull request #88 from rkwitt/Fix-VirtualEnvSetup

FIX: Virtual environment setup
Merge pull request #87 from thewtex/BasePythonTests

ENH: Use virtualenv for Base/ and Applications/ Python tests.
ENH: Add USE_VALGRIND option
ENH: Add USE_SYSTEM_CPPCHECK option and optional Cppcheck superbuild
BUG: Fix USE_SYSTEM_KWSTYLE and refactor find_program(KWStyle)
BUG: Various minor CMake related bugs and style fixes
ADD: Test for TubesToImage

     Added test for TubeTK application TubesToImage.
Merge pull request #90 from rkwitt/TubesToImage-Testing

ADD: Test for TubesToImage
Merge pull request #89 from jamiesnape/CMakeRelatedFixes

Various CMake-related bug fixes and enhancements
BUG: Fix CTK superbuild
COMP: Fix External_VTK CMake warning
ENH: Sync external project versions and arguments with Slicer
ADD: Test for TubeGraphToImage

     Added MIDAS keys + CMakeLists.txt for testing the TubeTK
     TubeGraphToImage Application.

     Commented out unused code.
ADD: Missing MIDAS keys for TubeGraphToImage testing.
ENH: New method for shrinking an image using a max function for summary