Fix issues in CMakeLists.txt + Refactor + Correct compiling warnings

In the root's CMakeLists I've changed the compiler-version check (I'm
using g++ 4.8.2 locally)

In the test's one, I had to insert the LOG4CXX include's directory..
normally it should find it automatically thanks to the other module,
but well.. it wasn't the case.


Plus:
1) Make the ProcessDecider a little bit smarter (still a couple of
things need to be done in order for it to be completely independent
from the message received)
2) There were some useless checks here and there, instead of
complaining with Michael I've fixed them. (checking if an unsigned int
is less than 0 is not that useful!)