add test coverage statistics

[lunebellec]

See https://github.com/codecov/example-python

[ltetrel]

Hmm not sure a code coverage is meaningfull for a project of this size..

[mathieuboudreau]

It's quite easy to set up for Github+Coveralls.io+Python. I find it useful for projects small or large.

See our setup for the AxonDeepSeg project (using Travis):

• https://github.com/neuropoly/axondeepseg/blob/master/.travis.yml
• https://github.com/neuropoly/axondeepseg/blob/b31988d532e25dbe125549946e6766ef569f7950/requirements.txt#L14-L15

[ltetrel]

Is it easy to plug it with circleCI (I see that you are using travis) ? I could give it a try if this is as simple as you mention.

In this project, there is basically one test per type of download, check.
So again, the coverage here is quite obvious here. I don't see obvious benefits for this project.