Upgraded celery to latest RC (RC4).
Closes
six>=1.11.0
cloudaux==1.4.13
-celery==4.2.0rc2
-celery[redis]==4.2.0rc2
+celery==4.2.0rc4
+celery[redis]==4.2.0rc4
redis==2.10.6
Flask==0.12.2 # Need to upgrade this with Flask-SqlAlchemy.
Flask-Mail==0.9.1
