Yasa

**Major update**

a. Added slow-waves detection for single and multi channel
b. Added `include` argument to select which values of `hypno` should be used as a mask.
c. New examples notebooks + changes in README
d. Minor improvements in performance (e.g. faster detrending)
e. Added html API (/html)
f. Travis and AppVeyor test for Python 3.5, 3.6 and 3.7

**Major update**
- Added support for multi-channel detection via spindles_detect_multi function.
- Added support for hypnogram mask
- Added several notebook examples
- Changed some default parameters to optimize behavior

- Added post-processing Isolation Forest
- Updated Readme and added support with Visbrain
- Added Cz full night in notebooks/

Initial release of YASA.