When trying to switch to a container that does not exist, it now removes that ctnr from the session list
When creating a ctnr, it is added to the users session variables. When deleting it is removed, and if user is currently in that ctnr they are switched to their default.
Edited for consistency
Merge branch 'master' of https://github.com/OSU-Net/cyder into ctnr_logic

Conflicts:
	cyder/base/views.py
Fixed ctnr_delete_session being called before permissions checking
Fixed another merge conflict
Fixed ctnr's not being deleted from ctnr session list properly
Ctnrs in session now update accordingly to name change
Fix ALLOW_OPTIONS
Fix ALLOW_OPTION precedence
Remove useless line

Maybe they meant 'ALLOW_OPTIONS = ALLOW_OPTIONS', in which case it would
actually do something, but we don't use it anyway so it's not an issue.
Disallow blank allow; set default to ALLOW_LEGACY
Improve constant names, values, and descriptions
Use if...elif... to make logic clearer
Add object to ctnr auto complete now works without having to select an option
Added error for non selected ranges in add object to ctnr form
Fix range_detail
Fix the order of ALLOW_OPTIONS in forms
Reorder constants for aesthetic reasons
Sort the allow list in the Range detail view