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
Resolve merge conflict