The UriDelegationPeer is used as a mechanism to pass arguments from
the UriArgManager which resides in "launcher space" to our argument
delegation service implementation that lives as an osgi bundle. An instance
of this peer is created from within the argument delegation service impl
and is registered with the UriArgManager.
uriArg - the uri argument that this delegate has to handle.
Called when the user has tried to launch a second instance of
SIP Communicator while a first one was already running. A typical
implementation of this method would simply bring the application on
focus but it may also show an error/information message to the user
notifying them that a second instance is not to be launched.