According to Openstack summit session [1],
stestr is maintained project to which all Openstack projects should migrate.
Let's switch to stestr as other projects have already moved to it.
[1] https://etherpad.openstack.org/p/YVR-python-pti
Change-Id: I0ec7bc7926e57b243e38b2c696815e648d0b3f61
Freezer currently uses pytest to execute unittests.
As we need to be consistent with the frameworks by the
other OS project, we are porting our tests to tests.
Change-Id: Ib755771efe496e467079dc2e990ca89a2e513eb6
Implements blueprint: swift-to-testr
Vu Cong Tuan