Add absolute_import to xgboost utils file

Author: edwardjkim

src/sagemaker/xgboost/utils.py

@@ -11,6 +11,8 @@
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
 """Placeholder docstring"""
+from __future__ import absolute_import
+
 from sagemaker.xgboost import defaults