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
Document build_ext --inplace before testing.

Otherwise we get a "ImportError: cannot import name _hmmc".
Merge pull request #11 from jdswinbank/docfix

Document build_ext --inplace before testing.
format change according to sklearn.
save unnecessary memory usage.
Merge pull request #13 from csytracy/master

Format change and saving memory.
Merge pull request #1 from hmmlearn/master

update