Turns Response into a QObject and sets parent to the
command that emits it.
Each Command is also a child of the decorator commands,
Timeout and PageLoading commnds, so that deleting the
top level command will delete all the children.
See discussion in #430.
Instead of emitting loadStarted when a reply is created and pageFinished
when all pending replies have finished, emit these signals when the
corresponding WebPage events fire.
Matthew Horan