Travis - lock google test framework to 1.8.0 for reproducible tests

Author: gjanssens

.travis.yml

@@ -17,5 +17,5 @@ install:
   - sudo apt-get install -qq swig
   - sudo apt-get install -qq libboost-all-dev
   - sudo apt-get --reinstall install -qq language-pack-en language-pack-fr
-  - git clone https://github.com/google/googletest ~/gtest
+  - git clone https://github.com/google/googletest ~/gtest && cd ~/gtest && git checkout release-1.8.0 && cd -
 script: ./autogen.sh && ./configure GTEST_ROOT=~/gtest/googletest GMOCK_ROOT=~/gtest/googlemock && make && TZ="America/Los_Angeles" make check