Fix test that would fail if reordered, or in a different timezone

tests/test_timestamper.py

@@ -1,5 +1,6 @@
 import nilmdb
 from nilmdb.utils.printf import *
+from nilmdb.utils import datetime_tz
 
 from nose.tools import *
 from nose.tools import assert_raises
@@ -19,6 +20,8 @@ class TestTimestamper(object):
         def join(list):
             return "\n".join(list) + "\n"
 
+        datetime_tz.localtz_set("America/New_York")
+
         start = nilmdb.utils.time.parse_time("03/24/2012")
         lines_in  = [ "hello", "world", "hello world", "# commented out" ]
         lines_out = [ "1332561600000000 hello",