[wip/certi] Introduce certi HEAD version

CERTI is an Open Source HLA RTI. HLA (High-Level Architecture) is a
general purpose architecture for distributed computer simulation
systems. In HLA systems, the RTI (RunTime Infrastructure) manages data
exchange between simulations. CERTI supports HLA 1.3 specifications (C++
and Java) and partial IEEE 1516-2000 (C++).