STYLE: Remove outdated cmake version support
STYLE: Remove outdated cmake version support

The minimum cmake version allowed is 2.8.6. Remove
conditional code to support cmake < 2.8.0.

Change-Id: Iad263d0aa141b415983875e4fa09b735ffaa463a

blowekamp/ITK,jcfr/ITK,zachary-williamson/ITK,malaterre/ITK,richardbeare/ITK,fedral/ITK,ajjl/ITK,msmolens/ITK,zachary-williamson/ITK,PlutoniumHeart/ITK,hjmjohnson/ITK,jmerkow/ITK,malaterre/ITK,Kitware/ITK,vfonov/ITK,jcfr/ITK,spinicist/ITK,biotrump/ITK,biotrump/ITK,LucHermitte/ITK,LucHermitte/ITK,msmolens/ITK,hjmjohnson/ITK,PlutoniumHeart/ITK,jcfr/ITK,Kitware/ITK,stnava/ITK,LucHermitte/ITK,thewtex/ITK,biotrump/ITK,InsightSoftwareConsortium/ITK,jmerkow/ITK,msmolens/ITK,malaterre/ITK,Kitware/ITK,fedral/ITK,blowekamp/ITK,BRAINSia/ITK,blowekamp/ITK,thewtex/ITK,fedral/ITK,ajjl/ITK,msmolens/ITK,jmerkow/ITK,blowekamp/ITK,fbudin69500/ITK,blowekamp/ITK,jmerkow/ITK,thewtex/ITK,LucasGandel/ITK,BlueBrain/ITK,richardbeare/ITK,Kitware/ITK,blowekamp/ITK,zachary-williamson/ITK,BlueBrain/ITK,spinicist/ITK,BRAINSia/ITK,PlutoniumHeart/ITK,fbudin69500/ITK,LucHermitte/ITK,zachary-williamson/ITK,jcfr/ITK,blowekamp/ITK,jmerkow/ITK,BRAINSia/ITK,jmerkow/ITK,stnava/ITK,jmerkow/ITK,LucasGandel/ITK,jmerkow/ITK,malaterre/ITK,spinicist/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,LucHermitte/ITK,jcfr/ITK,jcfr/ITK,malaterre/ITK,biotrump/ITK,spinicist/ITK,fbudin69500/ITK,thewtex/ITK,ajjl/ITK,fedral/ITK,fbudin69500/ITK,fedral/ITK,thewtex/ITK,richardbeare/ITK,vfonov/ITK,stnava/ITK,hjmjohnson/ITK,biotrump/ITK,vfonov/ITK,stnava/ITK,vfonov/ITK,vfonov/ITK,PlutoniumHeart/ITK,fedral/ITK,Kitware/ITK,BlueBrain/ITK,msmolens/ITK,biotrump/ITK,ajjl/ITK,stnava/ITK,blowekamp/ITK,msmolens/ITK,zachary-williamson/ITK,thewtex/ITK,jcfr/ITK,LucHermitte/ITK,stnava/ITK,PlutoniumHeart/ITK,msmolens/ITK,spinicist/ITK,BRAINSia/ITK,vfonov/ITK,spinicist/ITK,BlueBrain/ITK,biotrump/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,PlutoniumHeart/ITK,malaterre/ITK,BlueBrain/ITK,hjmjohnson/ITK,zachary-williamson/ITK,LucasGandel/ITK,stnava/ITK,BlueBrain/ITK,hjmjohnson/ITK,richardbeare/ITK,PlutoniumHeart/ITK,msmolens/ITK,InsightSoftwareConsortium/ITK,zachary-williamson/ITK,BRAINSia/ITK,BlueBrain/ITK,stnava/ITK,malaterre/ITK,LucasGandel/ITK,jcfr/ITK,fbudin69500/ITK,malaterre/ITK,ajjl/ITK,LucHermitte/ITK,malaterre/ITK,zachary-williamson/ITK,spinicist/ITK,LucasGandel/ITK,vfonov/ITK,fbudin69500/ITK,vfonov/ITK,richardbeare/ITK,fbudin69500/ITK,biotrump/ITK,BRAINSia/ITK,zachary-williamson/ITK,hjmjohnson/ITK,hjmjohnson/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,LucHermitte/ITK,LucasGandel/ITK,LucasGandel/ITK,ajjl/ITK,LucasGandel/ITK,spinicist/ITK,richardbeare/ITK,fbudin69500/ITK,stnava/ITK,spinicist/ITK,richardbeare/ITK,vfonov/ITK,fedral/ITK,BlueBrain/ITK,PlutoniumHeart/ITK,ajjl/ITK,InsightSoftwareConsortium/ITK,fedral/ITK,ajjl/ITK,thewtex/ITK,BRAINSia/ITK