Updates to category filters

- content is now no longer returned if the user has opted out of a
category
- A deactivated channel (top level) no longer appears in the channel
feed on the homepage
- Homepage features were subject to user preferences. This is no longer
the case
- Homepage picks were subject to user preferences. This is no longer
the case
- Categories that are turned off will no longer appear in the channel
feed
- Categories that are turned off will no longer appear within
sub-channel article listings
- new logger helper