Remove PY_TIMEZONE references (#547)

This changeset removes the PY_TIMEZONE configuration variable and updates all references to it to refer directly to pytz.utc instead.  It also cleans up a few of the import statements and removes those that are no longer needed (like the current_app reference from Flask).

Signed-off-by: Carlo Costino <carlo.costino@gsa.gov>

app/utils/time.py

@@ -2,11 +2,10 @@ from datetime import datetime
 
 import pytz
 from dateutil import parser
-from flask import current_app
 
 
 def get_current_financial_year():
-    now = datetime.now(current_app.config['PY_TIMEZONE'])
+    now = datetime.now(pytz.utc)
     current_month = int(now.strftime('%-m'))
     current_year = int(now.strftime('%Y'))
     return current_year if current_month > 9 else current_year - 1