Centralize algorithm imports

Algorithm.Python/PandasDataFrameHistoryAlgorithm.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");
@@ -11,20 +11,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from clr import AddReference
-AddReference("System")
-AddReference("QuantConnect.Algorithm")
-AddReference("QuantConnect.Indicators")
-AddReference("QuantConnect.Common")
-
-from System import *
-from QuantConnect import *
-from QuantConnect.Algorithm import *
-from QuantConnect.Indicators import *
-from QuantConnect.Python import PythonQuandl
-from QuantConnect.Securities.Equity import EquityExchange
-from QuantConnect.Data.UniverseSelection import Universe
-from datetime import datetime, timedelta
+from AlgorithmImports import *
 
 ### <summary>
 ### This algorithm demonstrates the various ways to handle History pandas DataFrame 
@@ -161,4 +148,4 @@ class PandasDataFrameHistoryAlgorithm(QCAlgorithm):
 class QuandlFuture(PythonQuandl):
     '''Custom quandl data type for setting customized value column name. Value column is used for the primary trading calculations and charting.'''
     def __init__(self):
-        self.ValueColumnName = "Settle"
+        self.ValueColumnName = "Settle"