* pin for pip version has been removed because it seems that the its "old"
dependency resolver doesn't work as expected
* testinfra package has been renamed to pytest-testinfra
* replaced `--constraint` with `-r` during packages installation
* in `tests/test_molecule.py` removed redudant append in finally block
Change-Id: Ifffc043ce88de9e67b1fde4654ecaa97530687e2
Signed-off-by: Roberto Alfieri <ralfieri@redhat.com>