Fail to run catkin_make install

[nicholasadr]

Running catkin_make install following the instruction here will fail with the following error:

...
-- Installing: //robots/meshes
CMake Error at robotiq/robotiq_description/cmake_install.cmake:72 (file):
  file INSTALL cannot make directory "//robots/meshes": No such file or
  directory
Call Stack (most recent call first):
  cmake_install.cmake:139 (include)

This is due to changes made in commit c1035e434654107ff2d739e06c41ef2e4cf1d844 in robotiq_description package.

[nicholasadr]

I'm working on a PR to fix this.