added gmock_catkin
updated gmock
Merge pull request #18 from ethz-asl/update/opencv2_catkin

update to "from source build opencv2_catkin"
Merge pull request #17 from ethz-asl/feature/gmock_catkin

added gmock_catkin
Revert "update to "from source build opencv2_catkin""
Merge pull request #19 from ethz-asl/revert-18-update/opencv2_catkin

Revert "update to "from source build opencv2_catkin""
updated opencv2