MAINT: Use print function instead of print statement.

The loader module printed some warning messages, these could
be changed to use a logger, but for now convert to use the print
function for compatibility with Python 3.

zipline/data/loader.py

@@ -156,10 +156,10 @@ def load_market_data(bm_symbol='^GSPC'):
     try:
         fp_bm = get_datafile(get_benchmark_filename(bm_symbol), "rb")
     except IOError:
-        print """
+        print("""
 data msgpacks aren't distributed with source.
 Fetching data from Yahoo Finance.
-""".strip()
+""").strip()
         dump_benchmarks(bm_symbol)
         fp_bm = get_datafile(get_benchmark_filename(bm_symbol), "rb")
 
@@ -192,10 +192,10 @@ Fetching data from Yahoo Finance.
     try:
         fp_tr = get_datafile('treasury_curves.msgpack', "rb")
     except IOError:
-        print """
+        print("""
 data msgpacks aren't distributed with source.
 Fetching data from data.treasury.gov
-""".strip()
+""").strip()
         dump_treasury_curves()
         fp_tr = get_datafile('treasury_curves.msgpack', "rb")