add default value for emailservice env var (#608)

fixes #607

The service was trying to run `.lower()` on an unset env var, resulting in spammy logs. I added a default value of false to the field to fix this

src/emailservice/email_server.py

@@ -121,7 +121,7 @@ def SendOrderConfirmation(self, request, context):
 class DummyEmailService(BaseEmailService):
   def SendOrderConfirmation(self, request, context):
     logger.info('A request to send order confirmation email to {} has been received.'.format(request.email))
-    if os.getenv('ENCODE_EMAIL').lower() == 'true':
+    if os.getenv('ENCODE_EMAIL', 'false').lower() == 'true':
       try:
         encoded_email = self.EncodeEmail(request.email)
         request.email = encoded_email