naming convention in coverage changed at version 4.0a0
pin coverage dependency
use tryfirst marker in load_initial_conftests
Merge pull request #25 from schlamar/tryfirst

use tryfirst marker in load_initial_conftests
Merge pull request #22 from bukzor/fix-coverage-pep8

naming convention in coverage changed at version 4.0a0
run tests with pypy3
do not run `assert True` in tests

This might be optimized out on pypy.
bump version
enable coveragerc [run]source (alternate implementation)
re-enable coverage 4
Merge branches 'enable-coveragerc.2' and 'coverage4'