added ltr/optimization/solver/particle_swarm_optimization.h
added ltr/optimization/solver/particle_swarm_optimization_unittest.cc
added ltr/optimization/population_udaters/particle_swarm_updater.h
updated cmake/ltr/cmake
updated cmake/utests.cmake

Change-Id: Ic4a76e99f84d719806de3b83a572fc43f56b5f70