ENH: Updating SimpelITK version to 0.7.0.dev54

This update to SimpleITK includes the following:
Fix for mantis 3157
Improved compilation time with parallelism
Improved VS9 compiler check
Windows numpy size conversions fix

Additional tweaks to external file include:
Adding cmake flag to remove git hash for version.
Adding cmake variables for git tag and url. Consistent with ITKv4 external
project description.
Remove extra CMake module include
Remove obsolete comment regarding unsupported shared library build. See r22133 [1]

[1] http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=22133

From: Bradley Lowekamp <blowekamp@mail.nih.gov>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22165 3bd1e089-480b-0410-8dfb-8563597acbee