Removes unused random source method.

Method was unused and used an unimported module.

zipline/utils/factory.py

@@ -174,20 +174,6 @@ def create_returns_from_list(returns, trading_calendar):
     return test_range
 
 
-def create_random_trade_source(sid, trade_count, trading_environment):
-    # create the source
-    source = RandomEquityTrades(sid, trade_count)
-
-    # make the period_end of trading_environment match
-    cur = trading_environment.first_open
-    one_day = timedelta(days=1)
-    for i in range(trade_count + 2):
-        cur = get_next_trading_dt(cur, one_day, trading_environment)
-    trading_environment.period_end = cur
-
-    return source
-
-
 def create_daily_trade_source(sids, trade_count, trading_environment,
                               concurrent=False):
     """