Merge branch 'FIX_gtest_new_api' into 'master'

Freeze google test version to v1.8.x (git branch)

See merge request mobile_robotics/wolf!210

src/test/gtest/CMakeLists.txt

@@ -21,6 +21,7 @@ set(GTEST_DISABLE_PTHREADS OFF)
 # Download GoogleTest
 ExternalProject_Add(googletest
     GIT_REPOSITORY https://github.com/google/googletest.git
+    GIT_TAG        v1.8.x
     # TIMEOUT 1 # We'll try this
     CMAKE_ARGS -DCMAKE_ARCHIVE_OUTPUT_DIRECTORY_DEBUG:PATH=DebugLibs
     -DCMAKE_ARCHIVE_OUTPUT_DIRECTORY_RELEASE:PATH=ReleaseLibs