Fixed failed coverage for coveralls.io. Adding coverage report for Gitlab.
- This fixed the failed converage report from coveralls.io, and filtered .env and some other tmp files from the report.
- This enabled the built in coverage report of Gitlab-ce. However, To get badge which can be navigated to a report like this, you need to enable gitlab page and configure that in the README.rst (I just don't know what's the corresponding url pattern of https://example.gitlab.io/ of this site is).
FYI, to display the badge from coveralls.io, you need to activate the github project on coveralls.io.
Edited by Dong Zhuang