vicon_sdk uses C++11 components

[danmox]

I added C++11 flags to fix the vicon_sdk compilation error.

[versatran01]

Prefer

set(CMAKE_CXX_STANDARD 11)

or

set_target_properties(myTarget PROPERTIES
    CXX_STANDARD 11
)

Just my thoughts.

[danmox]

CMAKE_CXX_STANDARD / CXX_STANDARD are available in cmake 3.1+ but the minimum version is set at 2.8.12, hence the use of add_compile_options.

I'm happy to use a more modern approach if you see no issue with bumping the cmake minimum required version to 3.1+.

[mike-watterson-ai]

The only issue would be with anyone still on 14.04, but I believe most people have upgraded by now.

[tdinesh]

There are some people still on 14.04. Also, the Fetch robot is also still at 14.04. Can you create a branch devel_indigo and then merge this in master? @mdkennedy3

[kartikmohta]

The whole package uses C++11 which was enabled in the main CMakeLists.txt, just that it was done after including the vicon_sdk subdirectory. I just pushed bbc1245 which I think is the simplest fix to this particular issue but we should "modernize" it at some point (probably after 14.04 is EOL).

[kartikmohta]

@danmox I'll delete the indigo-devel branch and close this PR for now. I created a separate issue (#12) for updating the cmake syntax when we don't need to support Ubuntu 14.04.