ci: add code coverage measurement while running the testing framework

[AngryMaciek]

I would suggest to hook this repo up to a code coverage measurement service (I use https://about.codecov.io/) and submit code coverage measurement there.
This can be divided into two tasks.

1. Use this package to run unit tests (defining the unittest engine) in the CI. This is essentially a wrapper package around unit testing packages(unittest, pytest, nose) that will additionally generate the line coverate report.
2. Submit the measurement to their website (also in the CI), according to their instructions.

I assume that what you have under motevowrapper/tests serves as unit tests for the whole project.
Well, let's see how many lines they cover ;)

They will also give you a fancy shield with a coverage % value, put it in the README as well!