Added top menu, tabbed browsing. The beginnings of the context page and the user...

Added top menu, tabbed browsing.  The beginnings of the context page and the user page are there.  Decision was made to distinguish between "system" and "customer" contexts so that a generic context editor could be used to manage the system.  There will now be a drop-down on the users page to select the appropriate customer.  It will be hidden if only one context is valid for the current user.  The same is already true for the contexts and global tabs.

git-svn-id: https://svn.alkaloid.net/gpl/shout/trunk@39 06cd67b6-e706-0410-b29e-9de616bca6e9