updated imports

Author: superplay1

c3/experiment.py

@@ -21,7 +21,7 @@
 from c3.generator.generator import Generator
 from c3.parametermap import ParameterMap
 from c3.signal.gates import Instruction
-from c3.system.model import Model
+from c3.model import Model
 from c3.utils.tf_utils import (
     tf_batch_propagate,
     tf_propagation_lind,

c3/main.py

@@ -10,7 +10,7 @@
 import tensorflow as tf
 from c3.parametermap import ParameterMap
 from c3.experiment import Experiment
-from c3.system.model import Model
+from c3.model import Model
 from c3.generator.generator import Generator
 
 logging.getLogger("tensorflow").disabled = True