add S3 config for Heroku deployment to production settings
remove static assets from S3 file storage;
"ImproperlyConfigured: The MEDIA_URL and STATIC_URL settings must have different values"
indicates that there is some conflict with re-using the S3_URL
add boto to requirements (required to store files on S3)
change constant variable names; boto apparently requires 'AWS_STORAGE_BUCKET_NAME' in settings.py
access S3 with http instead of https
remove https from S3 -- use http instead