In lieu of #283, implement Stackdriver Canary Analysis for use in GKE.

In cases like tsuru dashboard, he actually gets:

{
    "max ": [
        [1477493880000, 0.030500340632603404],
        [1477493940000, 0.04075857819905213],
        [1477494000000, 0.014717393483709273],
        [1477494060000, 0.029667878787878785],
        [1477494120000, 0.01438573566084788],
        [1477494180000, 0.01365384223918575],
        [1477494240000, 0.03254841309823678],
  

Web metrics currently support only GET requests against a URL, but I can imagine there are use cases where a different request method (i.e. POST, PUT) may be desired instead, along with parameterized payloads to go along with it.

The settings loading use pickle.load method
https://github.com/firstlookmedia/autocanary/blob/master/autocanary/settings.py#L61

which from the documentation:
https://docs.python.org/3/library/pickle.html

The pickle module is not secure against erroneous or maliciously constructed data. Never unpickle data received from an untrusted or unauthenticated source.

more information about how

Consider:

• environment variables;
• probabilistic evaluation;
• dumping evaluated feature flags.