STYLE: Make ordering of includes consistent

Following the 3D Slicer includes ordering rules for compatibility.

TubeTK
Boost
ITK
MetaIO
VCL/VNL
VTK
C standard library
C++ standard library

Change-Id: I9be273981021f93b0835b48d2b4b740431d85c61
Merge pull request #18 from jamiesnape/CleanupIncludes

STYLE: Make ordering of includes consistent