Make sites collection a global member of site_cache module
Allow for additional arguments to the site constructor
A thread safe getter for the site mod id
Fix get_mod_id_ts
Utilize cache when returning a list of allowed users
Simplify session caching.

Store only user_id in the session and retrieve user from
the site.users collection.
Functions to speedup users lookups by primary key
Avoid error prone default argument initialization
Do not use deprecated django.conf.urls.default
UI hints about delete operations that are in progress
UI hints about in progress grant access operations
A middleware to set X-Frame-Options and X-Content-Type-Options

To be used when wwwhisper is not run with nginx, which already
is configured to set these headers.
An utility method to test form-style post requests
Fix typo
Update 'title' tags
Refactor test cases
A method to check if a site has an open location
Move uuid generation responsibility to the collection base class
Model aliases
A view to manage aliases