moveit_ros_robot_interaction: linkedit error on OS X

When compiling `moveit_ros_robot_interaction` on OS X I get:

```
==> Processing catkin package: 'moveit_ros_robot_interaction'
==> Creating build directory: 'build_isolated/moveit_ros_robot_interaction'
==> Building with env: '/Users/william/moveit_ws/install_isolated/env.sh'
==> cmake /Users/william/moveit_ws/src/moveit_ros/robot_interaction -DCATKIN_DEVEL_PREFIX=/Users/william/moveit_ws/devel_isolated/moveit_ros_robot_interaction -DCMAKE_INSTALL_PREFIX=/Users/william/moveit_ws/install_isolated
-- The C compiler identification is Clang 4.2.0
-- The CXX compiler identification is Clang 4.2.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Boost version: 1.53.0
-- Found the following Boost libraries:
--   thread
-- Using CATKIN_DEVEL_PREFIX: /Users/william/moveit_ws/devel_isolated/moveit_ros_robot_interaction
-- Using CMAKE_PREFIX_PATH: /Users/william/moveit_ws/install_isolated
-- This workspace overlays: /Users/william/moveit_ws/install_isolated
-- Found PythonInterp: /usr/bin/python (found version "2.7.2")
-- Found PY_em: /Library/Python/2.7/site-packages/em.pyc
-- Found gtest: gtests will be built
-- Using CATKIN_TEST_RESULTS_DIR: /Users/william/moveit_ws/build_isolated/moveit_ros_robot_interaction/test_results
-- catkin 0.5.65
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/william/moveit_ws/build_isolated/moveit_ros_robot_interaction
==> make -j1 -l1 in '/Users/william/moveit_ws/build_isolated/moveit_ros_robot_interaction'
Scanning dependencies of target moveit_robot_interaction
[ 50%] Building CXX object CMakeFiles/moveit_robot_interaction.dir/src/interactive_marker_helpers.cpp.o
[100%] Building CXX object CMakeFiles/moveit_robot_interaction.dir/src/robot_interaction.cpp.o
Linking CXX shared library /Users/william/moveit_ws/devel_isolated/moveit_ros_robot_interaction/lib/libmoveit_robot_interaction.dylib
Undefined symbols for architecture x86_64:
  "tf::poseEigenToTF(Eigen::Transform<double, 3, 2, 0> const&, tf::Transform&)", referenced from:
      robot_interaction::RobotInteraction::addEndEffectorMarkers(boost::shared_ptr<robot_interaction::RobotInteraction::InteractionHandler> const&, robot_interaction::RobotInteraction::EndEffector const&, geometry_msgs::Pose_<std::allocator<void> > const&, visualization_msgs::InteractiveMarker_<std::allocator<void> >&) in robot_interaction.cpp.o
      robot_interaction::RobotInteraction::computeMarkerPose(boost::shared_ptr<robot_interaction::RobotInteraction::InteractionHandler> const&, robot_interaction::RobotInteraction::EndEffector const&, robot_state::RobotState const&, geometry_msgs::Pose_<std::allocator<void> >&, geometry_msgs::Pose_<std::allocator<void> >&) const in robot_interaction.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [/Users/william/moveit_ws/devel_isolated/moveit_ros_robot_interaction/lib/libmoveit_robot_interaction.dylib] Error 1
make[1]: *** [CMakeFiles/moveit_robot_interaction.dir/all] Error 2
make: *** [all] Error 2
Traceback (most recent call last):
  File "./src/catkin/bin/../python/catkin/builder.py", line 659, in build_workspace_isolated
    number=index + 1, of=len(ordered_packages)
  File "./src/catkin/bin/../python/catkin/builder.py", line 443, in build_package
    install, jobs, force_cmake, quiet, last_env, cmake_args, make_args
  File "./src/catkin/bin/../python/catkin/builder.py", line 297, in build_catkin_package
    run_command(make_cmd, build_dir, quiet)
  File "./src/catkin/bin/../python/catkin/builder.py", line 186, in run_command
    raise subprocess.CalledProcessError(proc.returncode, ' '.join(cmd))
CalledProcessError: Command '/Users/william/moveit_ws/install_isolated/env.sh make -j1 -l1' returned non-zero exit status 2
<== Failed to process package 'moveit_ros_robot_interaction':
  Command '/Users/william/moveit_ws/install_isolated/env.sh make -j1 -l1' returned non-zero exit status 2

Reproduce this error by running:
==> /Users/william/moveit_ws/install_isolated/env.sh make -j1 -l1

Command failed, exiting.
```

I have a fix for this, I'll open a pull request asap.