MAINT simplified `setup.py`

  Unlike the version inherited from `scikit-learn` the new version
  requires Cython to be installed
MAINT use conda in `.travis.yml`
MAINT replaced C classifier for Cython
MAINT install Cython when running on Travis
Randomize GMM initialization for GMMHMM.
Fix error in accumulating suff. stats for GMMHMM.
Add verbose reporting.
Fix observation checking for multinomial hmm.