Feature/206 move directory creation to storage

Created by: ghost

closes #206 (closed)

• small fix for the datetime warning during tests (use timezone aware now())
• new class for easier testing of PrivateStorage
• tests for new class

ran tests with RUN_E2E=true ./test.sh, all green.

reviewed by:

• @das-g
• @wasabideveloper

osmaxx-py/excerptconverter/converter_helper.py

 from django.contrib import messages
-#from django.core.mail import send_mail
 from django.utils.translation import ugettext_lazy as _
 
 import stored_messages