add rtt_common_msgs as an upstream dependency in Travis

Author: spd-intermodalics

.travis.yml

@@ -27,6 +27,7 @@ env:
   global: # global settings for all jobs
     - ROS_REPO=ros
     - CCACHE_DIR=$HOME/.ccache # enables C/C++ caching in industrial_ci
+    - UPSTREAM_WORKSPACE='github:orocos/rtt_common_msgs#master'
   matrix: # each line is a job
     - ROS_DISTRO="kinetic"
     #- ROS_DISTRO="melodic"