ENH: Require CMake >= 2.8.5 on Windows
ENH: Require CMake >= 2.8.5 on Windows

CMake 2.8.5 improves ITK's build on Windows in a few areas:

- Visual Studio 10 genertor bug fixes
- MinGW response files for long preprocessor include -I lists
- Fixed string(RANDOM) avoids parallel ExternalData download collisions

Tell users up front that they should use CMake 2.8.5 or greater rather
than waiting for them to encounter one of the problems it fixes.

Change-Id: Iccbcbc7fd280974245e0735fee884105b8cbe2d4

Kitware/ITK,thewtex/ITK,PlutoniumHeart/ITK,jcfr/ITK,LucasGandel/ITK,msmolens/ITK,blowekamp/ITK,BlueBrain/ITK,jmerkow/ITK,zachary-williamson/ITK,richardbeare/ITK,richardbeare/ITK,BlueBrain/ITK,stnava/ITK,malaterre/ITK,LucHermitte/ITK,jmerkow/ITK,spinicist/ITK,hendradarwin/ITK,LucasGandel/ITK,heimdali/ITK,BlueBrain/ITK,msmolens/ITK,Kitware/ITK,rhgong/itk-with-dom,biotrump/ITK,heimdali/ITK,stnava/ITK,atsnyder/ITK,thewtex/ITK,paulnovo/ITK,fedral/ITK,biotrump/ITK,zachary-williamson/ITK,BRAINSia/ITK,fuentesdt/InsightToolkit-dev,BRAINSia/ITK,spinicist/ITK,vfonov/ITK,msmolens/ITK,richardbeare/ITK,stnava/ITK,spinicist/ITK,hjmjohnson/ITK,BlueBrain/ITK,heimdali/ITK,hjmjohnson/ITK,LucHermitte/ITK,fbudin69500/ITK,thewtex/ITK,zachary-williamson/ITK,GEHC-Surgery/ITK,malaterre/ITK,jmerkow/ITK,heimdali/ITK,fbudin69500/ITK,LucHermitte/ITK,hendradarwin/ITK,jmerkow/ITK,blowekamp/ITK,paulnovo/ITK,CapeDrew/DCMTK-ITK,vfonov/ITK,fuentesdt/InsightToolkit-dev,hinerm/ITK,LucHermitte/ITK,jcfr/ITK,rhgong/itk-with-dom,ajjl/ITK,fbudin69500/ITK,fuentesdt/InsightToolkit-dev,paulnovo/ITK,jcfr/ITK,zachary-williamson/ITK,stnava/ITK,fuentesdt/InsightToolkit-dev,zachary-williamson/ITK,LucHermitte/ITK,rhgong/itk-with-dom,hendradarwin/ITK,eile/ITK,Kitware/ITK,fedral/ITK,atsnyder/ITK,hjmjohnson/ITK,hjmjohnson/ITK,heimdali/ITK,atsnyder/ITK,fuentesdt/InsightToolkit-dev,LucasGandel/ITK,hendradarwin/ITK,Kitware/ITK,thewtex/ITK,fedral/ITK,biotrump/ITK,jmerkow/ITK,fedral/ITK,hinerm/ITK,vfonov/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,CapeDrew/DCMTK-ITK,GEHC-Surgery/ITK,hinerm/ITK,PlutoniumHeart/ITK,jmerkow/ITK,BRAINSia/ITK,BlueBrain/ITK,hinerm/ITK,atsnyder/ITK,hendradarwin/ITK,CapeDrew/DCMTK-ITK,BRAINSia/ITK,stnava/ITK,CapeDrew/DCMTK-ITK,atsnyder/ITK,zachary-williamson/ITK,blowekamp/ITK,hendradarwin/ITK,hinerm/ITK,spinicist/ITK,eile/ITK,spinicist/ITK,atsnyder/ITK,spinicist/ITK,malaterre/ITK,paulnovo/ITK,stnava/ITK,jcfr/ITK,spinicist/ITK,jcfr/ITK,CapeDrew/DCMTK-ITK,LucHermitte/ITK,fbudin69500/ITK,biotrump/ITK,blowekamp/ITK,eile/ITK,zachary-williamson/ITK,blowekamp/ITK,richardbeare/ITK,hinerm/ITK,paulnovo/ITK,LucHermitte/ITK,CapeDrew/DCMTK-ITK,spinicist/ITK,hinerm/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,paulnovo/ITK,vfonov/ITK,atsnyder/ITK,rhgong/itk-with-dom,PlutoniumHeart/ITK,ajjl/ITK,ajjl/ITK,biotrump/ITK,LucasGandel/ITK,rhgong/itk-with-dom,fbudin69500/ITK,rhgong/itk-with-dom,eile/ITK,InsightSoftwareConsortium/ITK,msmolens/ITK,GEHC-Surgery/ITK,vfonov/ITK,stnava/ITK,CapeDrew/DCMTK-ITK,blowekamp/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,zachary-williamson/ITK,LucasGandel/ITK,eile/ITK,hinerm/ITK,InsightSoftwareConsortium/ITK,spinicist/ITK,vfonov/ITK,fuentesdt/InsightToolkit-dev,GEHC-Surgery/ITK,vfonov/ITK,biotrump/ITK,thewtex/ITK,rhgong/itk-with-dom,fuentesdt/InsightToolkit-dev,eile/ITK,ajjl/ITK,ajjl/ITK,blowekamp/ITK,BlueBrain/ITK,eile/ITK,LucasGandel/ITK,Kitware/ITK,ajjl/ITK,BlueBrain/ITK,eile/ITK,LucasGandel/ITK,jmerkow/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,vfonov/ITK,biotrump/ITK,malaterre/ITK,thewtex/ITK,Kitware/ITK,LucHermitte/ITK,ajjl/ITK,fuentesdt/InsightToolkit-dev,zachary-williamson/ITK,jcfr/ITK,malaterre/ITK,CapeDrew/DCMTK-ITK,GEHC-Surgery/ITK,blowekamp/ITK,malaterre/ITK,hjmjohnson/ITK,hinerm/ITK,richardbeare/ITK,msmolens/ITK,biotrump/ITK,fuentesdt/InsightToolkit-dev,richardbeare/ITK,malaterre/ITK,stnava/ITK,GEHC-Surgery/ITK,paulnovo/ITK,richardbeare/ITK,hendradarwin/ITK,malaterre/ITK,jcfr/ITK,hjmjohnson/ITK,rhgong/itk-with-dom,GEHC-Surgery/ITK,fedral/ITK,msmolens/ITK,fbudin69500/ITK,ajjl/ITK,msmolens/ITK,fbudin69500/ITK,InsightSoftwareConsortium/ITK,heimdali/ITK,jcfr/ITK,fedral/ITK,fedral/ITK,InsightSoftwareConsortium/ITK,CapeDrew/DCMTK-ITK,fedral/ITK,BRAINSia/ITK,malaterre/ITK,heimdali/ITK,atsnyder/ITK,Kitware/ITK,msmolens/ITK,hjmjohnson/ITK,hendradarwin/ITK,paulnovo/ITK,BlueBrain/ITK,PlutoniumHeart/ITK,PlutoniumHeart/ITK,heimdali/ITK,jmerkow/ITK,eile/ITK,PlutoniumHeart/ITK,GEHC-Surgery/ITK,atsnyder/ITK,LucasGandel/ITK,stnava/ITK