Move testtools to test-requirements.txt

The devstack-gate job is updated [1] to install packages from
test-requirements.txt. Hence move testtools from requirements.txt to
test-requirements.txt.

[1] https://review.openstack.org/64226

Change-Id: Ic3d3f4663bff64be91c23d9af46a3f766cbb7cf5
Configure solum service and endpoint in keystone

Change-Id: I7c43c6a50cd80df437412aa97d6fba71902e6da4