Add anomaly detection demo notebook and utils. Update Pipfile

The notebook in this commit is almost same as the ci/cd demo
notebook in the internal repo. The only changes are as follows
- remove query that identifies ci cd deployments internally, for
  privacy reasons
- update cache dir
- update markdown
- add grafana dashboard screenshot for a ci cluster, as the
  dashboard is not accessible outside VPN

utils.py is almost the same as prom_query.py used internally.
Only difference is that results are stored as parquet instead of
pickle format.

evaluate.py is a subset of utils.py used internally.

Pipfile

@@ -4,13 +4,26 @@ url = "https://pypi.org/simple"
 verify_ssl = true
 
 [dev-packages]
+black = "==20.8b1"
+nbdime = "*"
 flake8 = "*"
 coverage = "*"
 Sphinx = "*"
 
 [packages]
 src = {editable = true, path = "./"}
+ipywidgets = "*"
 awscli = "*"
+numpy = "*"
+scipy = "*"
+pandas = "*"
+pyarrow = "*"
+scikit-learn = "*"
+matplotlib = "*"
+seaborn = "*"
+prometheus-api-client = "*"
+hyperopt = "*"
+shap = "*"
 
 [requires]
-python_version = "3.8"
+python_version = "3.6"