add tests

[jeremymanning]

• create tests using TravisCI:

  • create a small sample dataset with a few scripts, and add to repo
  • parse into sliding windows
  • fit topic models to each script
  • segment into K events
  • compute trajectory in 3D (specify random seed)

• I suggest we try to support Python 3.6 and 3.7

• Also add web hook to Slack channel to notify us when tests complete

• Add a badge to the README file reporting the latest test status

[jeremymanning]

make modules out of functions in notebooks-- e.g. separate things out into importable python (.py) files (credit: @vassiki)