Removed 'import Operator' (#815)

Author: yaelbh

qiskit/advanced/aqua/chemistry/programmatic_approach.ipynb

@@ -48,7 +48,7 @@
     "from qiskit import Aer\n",
     "\n",
     "# lib from Qiskit Aqua\n",
-    "from qiskit.aqua import Operator, QuantumInstance\n",
+    "from qiskit.aqua import QuantumInstance\n",
     "from qiskit.aqua.algorithms import VQE, ExactEigensolver\n",
     "from qiskit.aqua.operators import Z2Symmetries\n",
     "from qiskit.aqua.components.optimizers import COBYLA\n",