Throw exception when using the bad method.
Fix the checkout options with the discovered exception

From the view configuration, if we request a time with a label based
configuration will throw an exception and the same happen with the time
based configuration. We adjuste the CheckoutOptions acording to this.
Fix time based problems when ending a importation.

Invalid state should be properly treated. For that we need to check the
type of configuration and if it is not time based, we will get the time of
the last modified item. We use the lastest because we assume that we are
now at the tip of the starteam view.
Merge remote-tracking branch 'origin/master' into label-support

Fix have been done for the view configuration state. Modification done
need to some more tuning to work properly with label based import.
Added some logic to find the label time when the janitor is needed.