Centralize algorithm imports

Algorithm.Python/CustomDataPropertiesRegressionAlgorithm.py

@@ -1,4 +1,4 @@
-# QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
+# QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
 # Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -11,21 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from clr import AddReference
-AddReference("System.Core")
-AddReference("QuantConnect.Common")
-AddReference("QuantConnect.Algorithm")
-AddReference("QuantConnect.Algorithm.Framework")
-
-from System import *
-from QuantConnect import *
-from QuantConnect.Algorithm import *
-from QuantConnect.Algorithm.Framework import *
-from QuantConnect.Data import SubscriptionDataSource
-from QuantConnect.Python import PythonData
-from QuantConnect.Securities import *
-
-from datetime import datetime, timedelta
+from AlgorithmImports import *
 import json
 
 ### <summary>
@@ -138,4 +124,4 @@ class Bitcoin(PythonData):
 
         except ValueError:
             # Do nothing, possible error in json decoding
-            return None
+            return None