[IMP] .coveragerrc: Allow to control decimal precision & min through env

[luisg123v]

It's now possible to control the following using environment variables:

• Decimal precision, usin $COVERAGE_PRECISION
• Minimum allowed coverage, using $COVERAGE_MIN
• Custom paths to exclude, using $EXCLUDE_COVERAGE

When the above variables are not set , values will fallback to their defaults, i.e. 0 in case of numeric values, or an empty string in case of custom paths (which has no effect).

For more information, please check the configuration reference of Coverage.py: https://coverage.readthedocs.io/en/coverage-5.0/config.html

Dummy MR

[luisg123v]

FYI @CarmenMiranda, it's now possible to specify decimal precision.