ucm shouldn't always start in the . namespace

[stew]

When we are exiting, we should save the current namespace somewhere so that the next time UCM starts it can start in that same namespace.

Also add a command line switch which can set the initial namespace so ucm --namespce=.would emulate the current behavior of always starting in the.namespace anducm --namespace=stew.share.publicwould start ucm in the.stew.share.public` namespace