Removes multithreading and time estimation from sampleMass
Incorporates sampleMass MCMC algorithm and fixes from Nathan Stein
Removes global accept/reject variables from sampleMass
Fixes a sampleMass bug
Fixes cmake build on OS X

Boost installs to a default include directory on Linux, but not on OS X. There was an ordering problem causing the yaml-cpp include dirs variable to be empty in base9, so OS X couldn't find Boost