Py-ms

**Configuration out of context**
Access to our YAML configuration out of Flask context.

See https://py-ms.readthedocs.io/en/latest/configuration/#import-configuration for more details

Fix error when Flask search for static files in wrong path

- fix/coveralls

- Resolve issue 34
Added __eq__ method to Config class to prevent errors

- Replace tracer Jaeger with Lightstep

We use [Opentracing](https://github.com/opentracing/opentracing-python) and [Opentracing Flask](https://github.com/opentracing-contrib/python-flask/tree/master/example) to trace all the requests. This lib needs a client and, actually, we work with [Jaeger](https://github.com/jaegertracing/jaeger-client-python).

I Replaced [Jaeger](https://github.com/jaegertracing/jaeger-client-python) with [Lightstep](https://github.com/lightstep/lightstep-tracer-python). I have compared both and Jaeger could be better but, at this moment, Jaegger have a lot of deprecated problems, for example:
* Not working with Flask-OpenTracing==1.0.0. use 0.2.0
* Not working with opentracing==2.0.0
* Use Tornado < 5. Tornado < 5 have security errors

When Jaeger will be updated, we replace in `pyms/tracer/main.py` the initialization of the tracer


- Added [Bandit](https://github.com/PyCQA/bandit) to static security analysis

- Added [Safety](https://github.com/pyupio/safetyt) to requirements security analysis

- Replaced unittest with [Pytest](https://docs.pytest.org/en/latest/)

- Added tests to docs

TYPE flask_request_count_created gauge
flask_request_count_created{endpoint="/",http_status="200",method="GET"} 1.5748102803254728e+09




TYPE python_logging_messages_total counter
python_logging_messages_total{level="INFO",service="Python Microservice"} 1.0
TYPE python_logging_messages_created gauge
python_logging_messages_created{level="INFO",service="Python Microservice"} 1.5748112738910015e+09

**Bugs fixed:**

* backward compatible requests service. If we have the old way to init requests raise a exception like:

pyms:
requests: true

First stable release

TYPE flask_request_latency_seconds_created gauge
flask_request_latency_seconds_created{endpoint="/",method="GET"} 1.5748102803253472e+09
HELP flask_request_count_total Flask Request Count
TYPE flask_request_count_total counter