COMP: Remove used flags to JsonCpp build.

For:

CMake Warning:
  Manually-specified variables were not used by the project:

      CMAKE_EXE_LINKER_FLAGS
      CMAKE_SHARED_LINKER_FLAGS
COMP: Only add -Wno-unused-local-typedefs for GCC.

Not found on clang 3.3.
BUG: Fix FindJsonCpp.cmake for finding the include directory.

The current version does not find the proper include directory.
Merge pull request #243 from thewtex/build

Build
BUG: Remove old debug code.
ENH: Tuner: Add widget to view and specify the metric space sampling.

A histogram of the values from the parameter progression is displayed in the
widget.
ENH: Bump SlicerExecutionModel to use updated FindJsonCpp
Merge pull request #244 from aylward/UpdateSlicerExecutionModel

ENH: Bump SlicerExecutionModel to use updated FindJsonCpp
ENH: Tuner: action to center metric sampling on convergence.

Towards obtaining the true peak value.
ENH: Tuner: spinbox to specify metric sampling.
ENH: Improve metric surface rendering.
ENH: Tuner, add a line plot of the progression.
Merge pull request #246 from thewtex/domain-specification

Domain specification