Revert "Remove unused import library"

Directive "from __future__ import print_function" is not an actual
import, but it enables print statement in py2 to behave like a real
function in py3.

This allows us to use print() function in py2/py3 compatible way.

This reverts commit 9910cbc746.

Change-Id: Ibdef82f0da42e815fd6c9ec632d0fd36c272b094

tackerclient/tacker/v1_0/vnfm/vnfd.py

@@ -15,6 +15,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from __future__ import print_function
+
 from oslo_serialization import jsonutils
 import yaml