Change to use GoogleTest for github repo with update
Change to use GoogleTest for github repo with update

The 1.8.0 release has issues with MSVC 2017. The usage of tr1 produces
a warning, and flags are enable so that warnings are enabled. The
selected version of GoogleTest is the same one that ITK is using has a
fix for the issue.

google/googletest#1111

kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix