Adding back mcmc files
MCMC module
Adding MCMC tests. Fixed some bugs in MCMC.

--HG--
rename : devel/mcmc.hpp => include/mcmc.hpp
rename : devel/mcmc.cpp => src/mcmc.cpp
Moving kernel parameter optimization to BayesOpt to consider other strategies (MCMC, etc.)
Reordering some elements to allow posterior distributions over criteria functions
Test MCMC file
Remove unnecessary parameters
Cleaning API and display demos
Removing or restricting elements from BayesOptBase to simplify API
Separate update hyperparams from fit GP.
MCMC implemented.
Missing abstract class for posterior.
Fixed issue with MCMC evaluation
Trying to combine MCMC with Hedging
Hedge working with MCMC, but quite unstable. Fixed some minor issues, like making private default and copy constructors for some classes.
Working on MCMC likelihood problems
MCMCSampler in log space to avoid rounding lik->0
Adding docs for MCMC
Cleanning display demos
Solving GL/GLUT issue in MacOS. Now it does not need FreeGLUT in MacOS.