Add NIW hyper-prior on mean and cov. Fix bug with evaluation of bound

The bug in the bound is us using expMeans after overwriting it with
just the means. The hyper prior seems to be necessary to avoid the
covariance collapsing to zero.
Change strength of prior in CTM
Calculate and return log-likelihoods as well as var-bounds when training
Now doing CTM Real data test on NIPS data
Like CTM/Bohning, STM/Bohning had a bug in how the var-bound was calculated.