cairomm: fix CMakeLists.txt

- Cairomm was not detected unless GKT is detected.
template: use a common VleUtilsConfig.cmake file

The VleUtilsConfig.cmake file is installed into share/cmake.
One can rely on thuis file rather than copying it into all packages.
CMake: handle version of cmake under 2.8.12

- the function target_include_directories was not defined
- linked libraries where concatened with ';' which leads to an error for old
versions of CMake.