Fix python code in cmake quoting issue reported by Hans Johnson

http://slicer-devel.65872.n3.nabble.com/CTK-CMake-warning-tt4030604.html
Merge pull request #430 from pieper/fix-quote

Fix python code in cmake quoting issue reported by Hans Johnson
COMP: Pass CMAKE_BUILD_TYPE to all projects

Thanks to Hans Johnson <hans-johnson@uiowa.edu> for reporting the issue.

See #418
Merge branch '418-support-use-system-option'

* 418-support-use-system-option:
  COMP: Pass CMAKE_BUILD_TYPE to all projects
Allow FindDCMTK.cmake to be re-used directly adding missing module.

Usage of 'find_package_handle_standard_args' was initially introduced
by commit 52d9539f5e7.

For more details about the issue, see http://forum.dcmtk.org/viewtopic.php?f=1&t=3906&p=15599#p15599

See #431
Merge branch '431-easier-re-use-of-finddcmtk'

* 431-easier-re-use-of-finddcmtk:
  Allow FindDCMTK.cmake to be re-used directly adding missing module.
COMP: Support CTK build using VTK6