change the way we include our own header files --> relative to the root - when plasma is in the same env, chameleon can take some headers not belonging to it (ex: #include descriptor.h, this file states in plasma install dir also) which make compilation errors

starpu_mpi_data_register is no longer a function but a macro in starpu-1.1, is replaced by starpu_mpi_data_register_comm

Avoid to add empty directories when checking a function in Finds - Fix errors in FindCHAMELEON.cmake

update the CMakeLists of chameleon to be more verbose about options set, remove set of cache for package dir (done inside Finds), remove some required non empty lists in find_package_handle_standard_args because it can be not defined in some case (without BLASEXT/LAPACKEXT)

fix problems in FindSTARPU: no more error if no min version are required, no more required flags for function testing --> error of -L empty

change installation directories for headers, executables and docs. Make it relative to chameleon to avoid a bloody mess in system dirs