McdDispatcher: add a concept of blocking dispatching until initial clients are ready
McdDispatcher: add a concept of blocking dispatching until initial clients are ready

This doesn't do actually delay anything yet.

freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control,freedesktop-unofficial-mirror/telepathy__telepathy-mission-control